midwest mapping project il

8/6/2019 Midwest Mapping Project IL

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By Michael P. McDonald

Midwest Mapping Project

IllInoIs

MIchIgan

MInnesota

ohIo

WIsconsIn

house


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Executive Summary

Redistricting is the drawing o legislative district boundaries. It usually occurs ollowing the decen-nial census so that districts will have approximately equal population and thus their constituents

will have approximately equal representation. However, there is much more to it. How districts are

drawn afects the ortunes o political parties, careers o incumbents, and representation o minori-

ties. Oen those who draw the districts are the same people who represent the districts, enabling an

abuse known as gerrymandering. During redistricting it is thus the case that representatives may

select voters rather than voters elect representatives.

A proposed solution to gerrymandering, and as a byproduct produce pleasing-looking districts, is

to have those who draw districts strictly ollow a set o neutral criteria. A computer might even be

programmed to automatically perorm this task. While this may sound like an attractive solution,

the Devil is in the details. Because people are not randomly scattered across the countryside, ap-

plication o ostensibly neutral criteria can intentionally or unintentionally have political efects. For

example, districts that respect city boundaries may overly concentrate supporters o a political party

i their supporters are clustered into dense urban areas. Instead o taking politics out o redistricting,

these neutral criteria may actually be a gerrymander in sheeps clothing.

Te purpose o this report is to investigate the potential efects o our criteria on the congressional

and state legislative districts that may be produced in the ve Midwestern states o Illinois, Michi-

gan, Minnesota, Ohio, and Wisconsin. o do so, congressional and state legislative plans are drawn

in accordance to our criteria, which are oen proposed as neutral criteria by reormers. Tere

are, o course, many other criteria that are oen proposed. Districts are drawn to look like squares

arrayed on a regular grid. Districts are drawn to be as compact as possible. Districts are drawn to re-

spect county boundaries. And districts are drawn to respect census place boundaries, which are cit-

ies, towns, and other governmental units that states and the Census Bureau work together to dene.

Tis mapping exercise demonstrates that it is practically di cult to achieve what may seem ideally

easy, such as drawing all districts to look like squares. Many practical details conound achieving

this ideal, perhaps the most important being that cities are densely populated. When districts must

be o equal population, as one moves rom densely populated urban areas to sparsely populated

rural areas, geographically smaller districts must give way to progressively larger districts. As a

consequence it is oen impossible to t districts together into nice shapes.

Tese our ways o drawing districts have predictable representational efects, both partisan and

racial. Tese efects are not always consistent or the our types o districts that are drawn across the

ve states or or the three types o legislative districts therein. Redistricting criteria should thus bethoughtully considered beore being adopted in any state. Tis is true even or diferent legislative

districts within the same state, since diferently sized districts such as large congressional districts

and small lower legislative chamber districts may interact with criteria in diferent ways.

An important lesson rom this report is that a one-size-ts-all approach to redistricting reorm will

not work in practice. Readers are encouraged to pay attention to all mapping scenarios within all

ve o these states. Doing so will illuminate the possibilities and limitations o redistricting reorm.

Tis mapping

exercise demon-

strates that it is

practically dif cult

to achieve what may

seem ideally easy.

Tese our ways o

drawing districts

have predictablerepresentational

eects, both partisan

and racial.

1 Introduction


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Acknowledgments

Tis report and the mapping project described herein were directed by Dr. Michael P. McDonald,

Associate Proessor o Government and Politics at George Mason University. Tis report made is

possible through painstaking mapping conducted by our George Mason University research assist-

ants: Nichole Claggett, Shaun Daniels, Gabriel Hudson, and Michael Keating. Helpul comments

on sections o this report were provided by Ann Henkener, Mike McCabe, Rich Robinson, and Rob

Richie. I am most grateul to odd Breitbart and Justin Levitt or their detailed comments o the

entire report. All errors remain my own. Tis project was generously unded by the Joyce Foundation

and benefted tremendously rom L arry Hansens participation. I would like to thank Caliper

Corporation or providing their mapping soware at a discount or this academic research. Finally,

I would like to thank the design team at Jasculca/erman and Associates or their expertise in pre-

paring this report.

Summary o Findings

Tis report examines redistricting within the fve Midwestern states o Illinois, Michigan, Minneso

ta, Ohio, and Wisconsin. For each state, congressional, upper legislative chamber, and lower legisla-

tive chamber districts are drawn under our criteria. Districts are drawn to look like squares arrayed

on a regular grid. Districts are drawn to be as compact as possible. Districts are drawn to respect

county boundaries. And districts are drawn to respect city boundaries. Te resulting collections o

districts known as redistricting plans are evaluated on their districts compactness, the number o

times districts split counties, their political composition, and their racial composition. Te mappin

oen reveals distinctive eatures o a state that aect redistricting, such as where people o dierent

races or political persuasion live or how natural eatures and political boundaries are laid out across

the state.

A summary o the lessons learned rom the mapping within each state is located at the beginning o

each states section. Some overarching themes emerge rom the state specifc fndings.

Where people live matters to redistricting. In particular, a proposed criterion may have predict-

able partisan or racial eects. Tis should seem-sel evident, but it is a simple act that that is oen

overlooked in redistricting reorm proposals.

Statewide plots showing where Democrats and Republicans live support the conventional wisdomthat Democrats tend to be concentrated within densely populated urban areas and Republicans ten

to be located within more sparsely populated suburban and rural areas. Te catch is that Democrati

communities tend to be places where ew Republicans live while Republican communities are inter

mixed with some Democrats.

Republican residential patterns tend to b e more e cient than Democrats rom a partisan gerry-

mandering standpoint.1 A gerrymandering strategy is to overly-concentrate an opponents sup-

porters into districts that they win easily. Tis technique to waste votes, known as packing, applies

Introduction 2 3 Introductio

Republican residen-

tial patterns tend

to be more ef cient

than Democrats

rom a partisan ger-

rymandering stand-

point.

able o Contents

Introduction

Summary o Findings p. 3

How to Draw Districts p. 5

Te Redistricting Data p. 6

Te Mapping Process p. 10

Map Statistics p. 12

Compactness Measures p. 14

Illinois

Overview p. 18

Congressional p. 22

State Legislature, Upper Chamber p. 32

State Legislature, Lower Chamber p. 42

Michigan

Overview p. 52

Congressional p. 56



Minnesota

Overview p. 86

Congressional p. 90



Ohio

Overview p. 120

Congressional p. 124



Wisconsin

Overview p. 154

Congressional p. 158



Endnotes p. 188


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to ederal Voting Rights requirements. Elsewhere, even though race is not s pecifcally considered

during map drawing, at least s ome minority-majority districts are drawn as a happenstance o

ollowing the our criteria. In Cleveland and Detroit, particularly, minority communities tend to

align along county and city lines. Some minority-majority districts are created when districts are

drawn that respect these political boundaries. Still, exploratory mapping to increase the number o

minority-majority districts indicates that there are some opportunities to do so beyond the number

realized in the 2000s plans i these political boundaries are crossed. In most instances, drawing test

plans ollowing the criteria used in this mapping project did not yield the same number o minority

majority districts as the adopted plan, which suggests that race may need to be taken into account t

satisy ederal Voting Rights requirements.

Te mapping reveals that there are practical limits to idealized districts that look like squares or

circles. For example, it is exceedingly di cult essentially impossible anywhere except perhaps or

Wyomings single congressional district to draw every district in a state to look like a square or

other compact shape. Densely-populated urban areas transition to sparsely-populated suburban an

rural areas. When equal population districts are overlaid on this population, districts must become

progressively larger in geographic size as population becomes more dispersed. As a result, there are

inevitably leover pieces in the transition zone that do not ft nicely into a district.

Tere are many ways proposed to measure a districts compactness. Te mapping reveals that these

compactness measures are related to specifc redistricting goals. Compactness measures that avor

minimal lengths o district perimeters tend to do well or square-shaped districts since census

blocks the building blocks o districts tend to ollow straight lines. Because census blocks do

not ollow circles, circular districts tend to are poorly on compactness measures avoring shorter

perimeter lengths and better on those that compare a district to an idealized circle. Districts drawn

around cities tend to are better on compactness measures that take into account where people live

within the district.

Te sum o our fndings is that one size does not ft all. Tis is true across states and across dierent

sized legislative districts within the same state. Toughtul consideration should be given to how

proposed redistricting criteria or legislative districts will interact with where a states residents live

Following neutral criteria, such as drawing districts to be squares or along some other seemingly

neutral criteria, may have predictable political consequences. I representational goals are a com-

ponent o a redistricting reorm proposal, these goals should be explicitly stated, rather than hoping

that a set o criteria will by ortunate happenstance produce a desired political outcome.

How to Draw Districts

o properly understand redistricting it is important to understand how to draw districts. Seemingly

technical details constrain redistricting in meaningul ways. For example, it is oen assumed even

by proessors that all groupings o individuals into districts are possible. However, this is not the

case. Practical geographic considerations actor in by the way the Census Bureau releases populatio

data to protect individuals confdentiality and by even the most modest requirement that districts

be compact.

5 Introductio

Toughtful consid-

eration should be

given to how pro-

posed redistricting

criteria for legisla-

tive districts will

interact with where

a states residents

live.

to any identifable group, including minorities. Because many Democrats tend to live in heavily

Democratic areas, districts that ollow neutral criteria will pack Democrats. Republicans are thus

generally observed to do better t han what their statewide strength would otherwise indicate among

the various test plans. Tere are comparatively more sae Democratic districts, while there are more

Republican-leaning competitive districts.

Unlocking Democrats rom urban centers can be achieved by drawing districts that tie together

Democratic urban areas and Republican suburban and rural areas. Depending on the degree by

which county or city boundaries overlay where people o dierent partisan stripes live, respecting

county or city borders can thus have predictable political consequences.

Democrats can be urther disadvantaged when large cities are located near a state border. In these

places the possibilities or unpacking Democrats are limited since a direction to draw districts is

unavailable. Tis dynamic occurs in Chicago, Illinois; Cincinnati, Ohio; Cleveland, Ohio; Detroit,

Michigan; and Milwaukee, Wisconsin.

Although geographic rules oen skew partisan representation in some instances, certain rules can have

a benefcial eect on partisan representativeness. Academics who study electoral systems around the

world note that single-member district systems tend to award the majority party with an additional

seat bonus above their share o votes. In an overwhelming Democratic state, a Democratic advantage

may be oset by the identifed redis tricting ine ciencies o where Democrats live, the reby making the

number o seats a party wins more reective o their statewide vote share. Te degree to which this is

true may depend on how districts are drawn in the remainder o a state. In Illinois and Michigan, the

ine ciencies o Democ rats concentrated in Chicago and Detroit may be parti ally oset by ollowing

criteria that result in consolidating mid-sized cities into Democratic-leaning districts. Tis is also true

in Wisconsin, though the rural areas o the state tend to be more balanced between Democrats and

Republicans than in other states examined in this report, urther mitigating the Republican advantage

realized during redistricting as a consequence o where people live.

Minnesota presents an interesting case o how the s ize o districts, relative to the size o cities, aects

the unpacking o Democrats. Te ideal equal-population or each o the states eight congressional

districts is 614,935 persons. Te ideal population or each o t he states one hundred and thirty-our

state House districts is 36,713 persons. In this relatively balanced battleground state, the partisan

composition o the congressional districts can reect the state as a whole i win Cities Democrats

are unpacked. Tis can be accomplished by drawing relatively compact districts that split the win

Cities core into our districts, grouping urban Democrats with suburban Republicans. ests plans o

State House districts exhibit more o a Republican advantage because these smaller districts cannot

bridge these urban and suburban areas. Tis disadvantage or Democrats is oset when plans are

specifcally drawn to respect census places, which creates additional Democratic districts Outstate

rom the win Cities. Interestingly, this Republican advantage is not mitigated among the statesslightly larger sixty-seven state Senate districts. Tese Senate districts tend to be larger than the

states mid-sized cities, as such these Senate districts must have a relatively greater mix o rural than

urban population compared to House districts.

Te ways by which the our ways o drawing districts aect racial representation is also examined.

Where minorities constitute a large enough population to constitute a majority o a district, minori-

ties tend to live in compact communities in urban centers. Illinois minority communities tend to be

the least compact o the fve states examined and thus require more consideration in order to adhere

INRODUCION

Introduction 4


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o illustrate, consider a map o the southern environs o Springfeld, Illinois. Census blocks appear

to mostly ollow roads and it is thus easy to identiy housing subdivisions on t his map. Note that no

all roads orm the border o a census block and not all census block borders are roads. City borders

water, and railroads also orm census block borders. In the top middle o the map, a census block

boundary cuts across an open feld, ollowing an old rail be d.

Some people suggest that states should be divided into square districts, but this map should disabus

anyone o the notion that square districts are easy to draw. Roads, terrain, and political boundaries

simply are not arrayed onto a ready-made grid.

Certainly, some o the limitations census geography places on redistricting are inconsequential, suc

as the intersection o I-55 and I-72 that orms the diamond-shape in the upper right-hand quadran

o the map. No one lives between the overpass and the connecting ramps, yet the Census Bureau ha

seen ft to designate these areas as s eparate census blocks. One might split or assign census blocks

such as these to more than one district without aecting districts populations. However, to split

census blocks where people live requires urther justifcation. Districts must be o equal population

so how the split divides a blocks population would need to be determined through sources other

than census data.

A urther complication that rustrates map drawing is that cities oen do not have regular boundar-

ies. An arm o Lake Springfeld, located along the bottom o the map, is within the city o Springfeld.

Some homes along the lake are incorporated within the city, while others remain within the county.

Tese annexation decisions have created oddly-shaped city borders throughout the map. Tere are

several examples o cities completely encompassed by larger cities, such as the city o Bexley located

within Columbus, Ohio and Hamtramck and Highland Park located within Detroit, Michigan.

A close examination o the map, particularly along the lake but also elsewhere, reveals that some

homes are actually located on islands o county land isolated within the city. In redistricting

terminology, these islands are non-contiguous to t he county proper. I one were to draw a district

composed solely o Springfeld, these islands would pose a quandary since contiguity is considered

a relatively non-controversial criterion that is sometimes even required by law.

Population Data: Redistricting occurs at least once a decade because in the 1960s the United State

Supreme Court interpreted the ederal constitution to require that districts be o substantially equa

population.3 At the time, s ome states had not redistricted or decades, creating severe population

imbalances between ast growing urban areas and slower growth rural areas. People living in under

populated rural districts were thereby aorded more representation than people living in overpopu

lated urban districts. Te equal population requirement means that redistricting now occurs at t he

start o each decade when population shis are revealed by a new decennial census.

Te 2000 census population data reported in t he Census Bureaus PL94-171 redistricting data fle,

which is so-called aer t he ederal law which mandates its release or redistricting purposes, are

used or mapping. Te PL94-171 fle is among the frst data that the Census Bureau releases ollow-

ing the decennial census. Processing decennial census data is a laborious task, and only a limited

amount o inormation is released in the PL94-171 fle. Te fle reports or all census blocks the tota

number o persons, those o voting age, and these statistics by race. Te race inormation enables

the drawing o districts that provide minority communities opportunities to elect candidates o the

choice, as required by the ederal Voting Rights Act.

7 Introductio

When districts are drawn, people do not s imply take a crayon to a piece o paper. Enormous

amounts o geospatial, population and election data are processed by computers and analyzed by

map drawers to ensure that the resulting districts conorm to ederal and state criteria and that the

redistricting plans will be politically acceptable to those who must vote to adopt them.

HE REDISRICING DAA

Redistricting data sets have three important components. Tere are geospatial data, which in the

world o modern technology are a digital representation o maps produced by the Census Bureau.

Tere are population data which the Census Bureau associates with their digital maps. And there are

election data that a redistricting authority may associate with the digital maps.

Geospatial Data: Trough the marvels o modern technology, the Census Bureau has digitally

mapped the entire country. Tis technological advancement is actually widely used, though most

people do not think much about it. It enables someone to look up a street address and plot direc-

tions rom their house to a destination o their choice.

Te Census Bureau does not publicly release their data in such a way that permits an individual

to look up an address to see how the people living there flled out their census orms. Te Census

Bureau is required by ederal law to protect individuals confdentiality. Tey do so by aggregating

individuals responses within geographic units, collectively known as census geography.

Te smallest piece o census geography is known as a census block. As the name implies, a census

block may be equivalent to a city block in a densely populated urban area. Tey are oen much

larger in rural areas. Tese blocks may be aggregated into block groups and tracts. Te Census

Bureau defnes other geospatial eatures that ollow existing political boundaries, such as county and

state borders. A special type o geography are census places. Te Census Bureau works with states

and their local governments to defne entities that they believe have a distinct identity, which may

depending upon the state include unincorporated areas, villages, townships, towns, cities, and

municipalities. Other spatial data are oen available such as man-made roads and railroads, and

natural eatures such as rivers and lakes.2

INRODUCION

Introduction 6

Map Legend

Block boundaries

Rail Roads

Census places

Bodies of water


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Census population data are supplemented with election data to measure the political consequences

o particular redistricting plans. Minnesota, Ohio, and Wisconsin election data merged to census

data during their redistricting eforts were obtained. For Illinois and Michigan, a database o elec-

tion and census data was constructed.

Several steps are required to merge together census population data and election results. Voting

tabulation districts are larger than census blocks, so the election data must be disaggregated to

this lower level o geography. Te approach used here is to apportion votes to census blocks as a

proportion o a census blocks voting-age population (persons age 18 and older) within each voting

tabulation district. For example, i a census blocks voting-age population constituted 25% o a vot-

ing tabulation district and George W. Bush received 100 votes there, then 25 Bush votes would be

assigned to the census block. Similar approaches were used by data consultants in Minnesota, Ohio

and Wisconsin to produce their redistricting databases.

Te 2000 presidential general election results are analyzed in this report, or two reasons. First,

redistricting authorities oen examine results rom several elections and registration data, as well.

However, in order to make valid comparisons across the ve states, election results or a common

o ce like the presidency must be analyzed. Fortunately, the 2000 presidential election was closely

contested, thus ofering a good measure or districts partisanship.

Second, 1996 and 2004 presidential data might have been examined. However, as a practical matter

o the time and efort o merging together election and census data, analysis was limited to the 2000

presidential general election. Tis is illustrated by the steps taken to merge 2000 election results wit

census population data.

States transmitted their 1998 voting tabulation districts to the Census Bureau. Localities may split o

consolidate their voting tabulation districts rom one election to the next. Tis creates uncertainty

or the correspondence between the voting tabulation districts used in t he 2000 election and censu

blocks. Approximately one percent o Illinois and Michigans 2000 general election voting tabulatio

districts that were split or consolidated between 1998 and 2000 had no clear match to 1998 census

designated voting tabulation districts. In these cases, election results rom the 2000 voting tabulatio

districts were matched with the 1998 voting tabulation districts or unassigned census blocks were

assumed to correspond with an unassigned voting tabulation district. In some cases, particularly

where a new voting tabulation district was ormed in 2000, no inormation was available to assign

the voting tabulation district to census blocks.

Fortunately, the induced error in these cases is typically small since voting patterns in adjacent vot-

ing tabulation districts tend to be similar. Tese assignments are very time consuming because they

require human inspection. Further merging o 1996 and 2004 election data would have likely have

resulted in similar issues.

Matching o election and census data is also incomplete where election absentee ballot results are

reported in separate absentee ballot precincts that have no clear correspondence to census geogra-

phy, such as is the case or Detroit, Michigan. Absentee votes are not assigned to census geography;

however, the error this causes should be small since these states early voting rates in the 2000 elec-

tion were low.

9 Introductio

More up-to-date population data might be desired to orecast the current impact o redistricting

criteria. Unortunately, such population data are not available at the census block level between

censuses. Some data at higher levels o aggregation provide indications o what may happen aer the

next census. Te Census Bureau releases population estimates at the state and county level, which

are used to orecast which states may gain or lose congressional seats through apportionment, which

is the awarding o House o Representative districts to the states based on population as required

by the United States constitution. Tese data also provide clues as to how congressional and state

legislative districts may be arrayed across regions within a state aer the next decennial census.

Starting in 2005, the census long orm the more detailed economic and socio-demographic data

collected rom a sample o American households is now available during redistricting, where

beore it was released aer redistricting. In 2005, the Census Bureau conducted the rst American

Community Survey, also known by its acronym ACS, which is a yearly replacement or the census

long orm. Te Census Bureau distributes the ACS every year to one in a hundred households, as it

did previously or the decennial census long orm. Te ACS includes several important demographic

questions, such as income and education, and relevant or voting rights purposes asks citizenship

status. Te three year average o t he American Community Survey provides statistics down to t he

block group level (collections o blocks) in some areas, but or condentiality reasons these data

cannot be released at the census block level where there may be ew ACS respondents.

Election Data: Tose who draw district lines oen consider their political consequences. o evalu-

ate the political ramications o their actions, they merge together election data with census geogra-phy known as voting tabulation districts, which are townships, precincts or wards, depending on

what a state calls their election units.

As a map o the area around the Wisconsin st ate capital in downtown Madison, Wisconsin demon-

strates, voting tabulation districts are oen composed o several census blocks. Te correspondence

is not by chance. Te Census Bureau works with states to map voting tabulation districts onto

census geography prior to the decennial census during what is known as Phase wo o the census

redistricting data program.4 Tis permits a rather straightorward matching o election and census

data, though there are instances where a census block may be split by a voting tabulation district.

INRODUCION

Introduction 8

Map Legend

Block boundaries

Precinct boundaries

Bodies of water


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Mapping starts with grid plans, where a best attempt is made to draw districts shaped like squares

arrayed on a regular grid. Because states and even census blocks are not always perect squares, ev-

ery district cannot be a perect square. A urther dif culty in drawing nicely-shaped squares is that

the population is unevenly concentrated throughout a state, in sparsely populated rural areas and

heavily populated urban centers. Despite these complications, grid maps are sometimes proposed a

starting points or urther renements on other criteria. Our grid plans serve a similar purpose by

providing map drawing practice in a st ate and identiying areas that may require special attention in

subsequent mapping.

Mapping proceeded next to compact plans. Compactness is a requently cited criterion or reorm

eorts since it is believed that oddly-shaped tentacles and other strangely-shaped non-compact

districts are indicators o political chicanery.

Compactness can be measured in multiple ways, and is oen s aid to be, like beauty, in the eye o th

beholder. Te mapping soware Maptitude generates seven measures o district compactness, which

are described on page 14. Tese measures dier on how they are calculated. A district may be con-

sidered to be compact i it looks like a circle and has ew jagged edges. In some cases, these compac

districts look similar to those drawn or a grid plan, with the exception that districts are allowed

to be taken o a grid so that they might better t together. Districts are drawn with these goals in

mind, rather than trying to maximize a particular compactness measure.

Te next plans drawn minimize the number of county splits. Districts that ollow political bound

aries like counties and other government jurisdictions help keep these communities intact. Arrang

ing districts along existing political boundaries may also help minimize election administration

costs by minimizing the number o jurisdictions that need to hold elections or a district. Districts

that respect county or census place boundaries oen require the creation o ewer voting tabulation

districts and related polling places since voting tabulation districts oen cannot cross district

and existing political boundaries. Crossing a county line might thus create two voting tabulation

districts where only one might otherwise be necessary.

Not all counties can be kept whole. A county with a population that is larger than the ideal popula-

tion size o a district must be split between two or more districts. It is not always possible, either, to

group counties that have populations below the ideal population or a district into a legal popula-

tion- sized district.

Tere are multiple ways to count county splits. Consider a county with three whole or parts o dis-

tricts contained within. Te county might be considered split three times by three districts, or once

by two or more districts. Te rst counting method is used when drawing these test plans, which

counts the number o districts within each county when two or more districts are present and then

sums across all counties. Tis c ounting method produces a higher number o county splits when asingle large-population county has many districts within it, and thereore penalizes a mapping strat

egy that cannibalizes a large county by repeatedly slicing it to round up under-populated districts in

adjacent counties.

Te next plans are those that minimize the number of census place splits . As mentioned previ-

ously, the Census Bureau works with states and their local governments to dene entities that they

believe have a distinct identity, which may depending upon the state include unincorporated

areas, villages, townships, towns, cities, and municipalities. Following these political boundaries

MAPPING SCENARIOS

Grid Plans: Districts that divide a state

into square blocks.

Compact Plans: Districts that create

visually compact districts, often lookinglike circles where possible.

County Splits Plans: Districts that

minimize the number of split counties.

Political Subdivision Plans: Districts

that minimize the number of split census

places, such as townships, cities, and

municipalities.

11 Introductio

HE MAPPING PROCESS

For over a year, rom the all o 2006 and extending through the end o 2007, our research assistants

drew congressional and upper and lower chamber s tate legislative plans or Illinois, Michigan, Min-

nesota, Ohio, and Wisconsin. A computerized commercial mapping program known as Maptitude

was purchased rom the Caliper Corporation at an academic discount and run on our computers

generously provided ree o charge by the George Mason University Geography Department. In all,

over 16,500 individual districts were drawn as part o this mapping project.

Redistricting plans were drawn by our research assistants. Each research assistant was t asked with

drawing a set o plans or each o the three legislative bodies under our criteria scenarios. For all

practical purposes there are nearly an innite number o ways o assigning the hundreds o thou-

sands o census blocks to districts within a state. All district congurations thereore cannot be ex-

plored. However, by analyzing plans drawn by our separate individuals any personal idiosyncrasies

that sneak into an individuals mapping, such as a tendency to always start drawing rom the upper

right corner, will not overly bias this reports ndings.

All districts are commonly drawn under two constraints.

First, districts must be contiguous, that is, they have to internally connect. Districts that connect

at a point, where the only corners o two census blocks touch one another, are not considered to be

connected.

Second, districts must be oequal population. Te ideal population size o a district is computed by

dividing the population o the state by the number o districts. Tere are dierent standards or how

much congressional and state legislative districts may deviate rom the ideal population without

inviting a legal challenge. Legal s cholars generally recognize that congressional districts must deviate

by at most one person rom the ideal in order or a state to avoid a potential ederal legal challenge

to the constitutionality o a states redistricting plan. I a states population is neatly divisible by the

number o congressional districts, the districts must be o absolute equal population. In practice,

drawing such nely-balanced districts is painstaking. It requires hunting and pecking or census

blocks around the perimeter o a district that make its population achieve equality.

o cut down on time costs, a rule was adopted whereby a congressional district could deviate as

much as plus or minus 1% rom the ideal population. Te U.S. Supreme Court is more lenient or

state legislative districts, permitting the population o the largest and smallest districts to deviate by

up to 10% in most instances. A version o this population deviation limit was adopted or our state

legislative districts, requiring that no district deviate by more or less than 5% rom the ideal popula-

tion, although states may impose more strict standards.

Tis report is organized into sections or each o the ve states. An overview o t he state is provided

at the beginning o each state chapter, with a summary o the ndings rom the mapping exercises.

Tese detailed ndings are discussed in three parts, one or congressional districts, one or the

upper state legislative chamber, and one or the lower legislative chamber. At the beginning o each

part, districts adopted or use during the 2000s decade are described and the possibilities or maxi-

mizing the number o minority-majority districts are discussed. Tis is ollowed with a discussion o

the redistricting plans that are drawn under each o our scenarios: grid, compact, minimization o

county splits, and minimization o census place splits.

INRODUCION

Introduction 10


8/30

Compactness: Many ways have been proposed to measure the compactness o districts. Tese man

measures may consider districts perimeter, area, population, or combinations o all three. By one

count, there are over thirty proposed compactness measures. More are be ing proposed all the time.

In act, the number o measures is so great that s ome are occasionally rediscovered.

Te mathematical ormulas or compactness measures can be conusing, s o those wishing to under

stand compactness measures should read this discussion careully.

Compactness measures are ofen named afer the people who rst proposed them. Our mapping

sofware, Maptitude, computes seven o these measures.5 For all but the Perimeter and S chwartzber

tests, the measures range b etween zero and one, with the higher value o one indicating the most

compact district. For these two other measures, a lower value indicates a more compact district.

Many compactness measures compare a districts shape to an idealized circle, since a circle is ofen

regarded as the most compact shape. A circle is the shape with the shortest perimeter that can en-

close a given area. However, like packing marbles in a jar, every district cannot be a circle since the

would be unassigned spaces between districts. Other practical considerations intrude on creating a

ideally compact district. State borders are ofen not regularly shaped, particularly where they ollow

bodies o water. Within states, districts may need to ollow irregularly shaped natural eatures and

man-made eatures, such as city boundaries.

Further detrimental to compactness is that districts must be o equal population. Geographically

smaller districts must be drawn in urban areas. Districts become progressively larger in size as they

are drawn over less densely populated suburban and rural areas. Fitting together these dierent-

sized districts in a compact manner is a challenge. Ofen, oddly-shaped lefover pieces occur in the

transition rom urban to rural areas.

Tese complications are part o the reason why so many compactness measures have been proposed.

Justice Stewarts classic denition o obscenity you know it when you see it has generally been the

guiding principal or identiying when a district is bizarre in shape, to use Justice OConners termi-

nology, rather than dening an explicit mathematical ormula. Our mapping exercise demonstrates

that districts drawn with dierent goals in mind may be considered more compact under some com-

pactness measures compared to others. Tus, it may be inormative to consider multiple compactness

measures when analyzing the compactness o a given district or overall redistricting plan.

Tese compactness measures are best interpreted when comparing redistricting plans within a

given state. Dierent external and internal state boundaries conound between-state comparisons

o compactness. Comparisons o congressional and state legislative districts within states may also

not be entirely comparable since districts may necessarily ollow dierent boundaries due to their

relative sizes.

13 Introductio

Tose wishing to

understand com-

pactness measures

should read this

discussion carefully.

helps keep these communities intact and promotes representation, particularly where oddly shaped

city boundaries result rom ideologically motivated annexation battles. Such districts may, similar to

those that minimize county splits, also help minimize election administration costs. As the preced-

ing example o Springeld, Illinois demonstrates, census places may have strange shapes or imbed-

ded pockets o unincorporated land within their boundaries. A ew census places may even cross

county boundaries. For these plans that minimize census place splits, preerence is given to splitting

counties over splitting census places.

Tese redistricting plans do n ot consider the racial representation goals mandated in the Voting

Rights Act. Racial bloc voting analyses ofen examine patterns o white and minority voting in

several elections to determine levels o racial support or candidates, which is used to determine the

su cient percentage o minorities within a district in order or a minority group to have the op-

portunity to elect a candidate o their choice. Tis project did not have the capacity to conduct racial

bloc voting analyses.

For every legislative chamber examined here, redistricting plans were drawn to maximize the num-

ber o minority-majority districts. In drawing these plans, a minority-majority district is dened as

one with a single minority group comprising a majority o a districts population, Arican-American

or Hispanic. A coalition district, whereby two or more minority groups constitute a majority, does

not count as a minority-majority district.

I the map drawers were able to draw more minority-majority districts than the plan adopted or use

in the 2000s decade, the section describing these adopted districts discusses these options. State-

wide plans that maximize the number o minority-majority districts were not drawn since it is not

clear which criteria should be applied to the districts outside the minority communities. Statistics

or such plans would be contingent on the minority districts and the approaches used to draw other

districts, and thereore may be misleading.

MAP SAISICS

Detailed reports o district-level statistics were generated or each plan. Tere is insu cient space in

this report to report statistics or each plans districts. Such inormation would not truly be inorma-

tive since there would be some 16,500 individual districts to sif through. So, various summary sta-

tistics are provided or all plans drawn under a mapping scenario or congressional, upper chamber

and lower chamber state legislative plans.

Tese plan summary statistics include district measures o the number o county splits, compact-

ness, racial composition, and partisan leanings.

Number of County Splits: Te number o counties split by districts is counted as the sum o the

number o districts within each county, or all counties with more than one district. For example,

i a county contains two districts, whole or in part, then it is split twice. A county or collection o

counties with one district are not counted as being split. Te average number o county splits across

all plans o a given plan type is reported.

INRODUCION

Introduction 12

Tese redistrict-

ing plans do not

consider the racial

representation goals

mandated in the

Voting Rights Act.


9/30

Te Schwartzberg Measure

Te Schwartzberg Measure has three steps and tries not to penalize districts that

have odd shapes due to natural eatures or political boundaries. In the frst step, a

simplifed version o the district is created that eectively excludes odd peripheral

eatures due to water or an adjoining state, or example. In the second step, the

perimeter o a circle with the same area as the simplifed district is computed. In

the third step, the ratio o the perimeter o the simplifed district to the perimeter

o the circle is computed. Tis measure tends to penalize districts with one or mor

tentacles or with many jagged edges, but does not penalize a district i the jagged

edges are a consequence o external boundaries.

For the Schwartzberg measure, a smaller number indicates a more compact

district. A perectly compact district scores as one and larger numbers as less

compact. (Te average Schwartzberg test score or all districts is reported or each

map type.)

Te Population Circle Measure

Te Population Circle Measure, like the Roeck measure, draws the smallest pos-

sible circle around a district. Instead o comparing areas, the measure is the ratio

o a districts populations to that o the enclosing circle. Tis measure thereore

does not penalize districts heavily or ailing to include peripheral territory that

has little or no population, such as water. Districts drawn around population cen-

ters tend to are well using this measure.

Te Population Circle measure varies between zero and one. Larger numbers

indicate a more compact district. (Te average Population Circle measure or all

districts is reported or each map type.)

Te Population Polygon Measure

Te Population Polygon Measure is similar to the Population Circle test in that

its primary consideration is population rather than area. Instead o a circle drawn

around a district, the minimum convex enclosing shape (i.e., it cannot bow

inwards) is drawn around the district. Te ratio o a districts population to thisconvex polygon is then computed.

Te Population Polygon measure varies between zero and one. Larger numbers

indicate a more compact district. (Te average Population Polygon measure or al


15 Introductio

Te Perimeter Measure

Te Perimeter Measure is perhaps the simplest o all compactness measures. It is

simply the length o a districts perimeter. Districts with relatively straight edges

tend to score as more compact by this measure while those with jagged edges tend

to have longer perimeters.

Te Perimeter Measure ranges rom zero to infnity. A smaller number indicates

a more compact district. (Te average sum o all district perimeters is reported or

each map type.)

Te Roeck Measure

Te Roeck Measure is the ratio o a districts area to that o the s mallest circle that

can be drawn to enclose the entire district. Tis test penalizes districts that may

have one or more tentacles reaching rom the district core.

Te Roeck measure varies between zero and one. Larger numbers indicate a

more compact district. (Te average Roeck measure or all districts is reported or

each map type.)

Te Ehrenburg Measure

Te Ehrenburg Measure is the ratio o the area o the largest circle that can be

drawn inside a district to area o the district. Tis test penalizes districts that may

have one or more tentacles reaching rom the district core.

Te Ehrenburg measure varies between zero and one. Larger numbers indicate a

more compact district. (Te average Ehrenburg measure or all districts is reported

or each map type.)

Te Polsby-Popper Measure

Te Polsby-Popper Measure has two steps. In the frst step, the area o circle with

the same perimeter length as the district is computed. In the second step, the ratioo the area o the district to the area o the circle is computed. Tis measure tends

to penalize districts with one or more tentacles or with many jagged edges.

Te Polsby-Popper measure varies between zero and one. Larger numbers

indicate a more compact district. (Te average Polsby-Popper measure score or all


INRODUCION

Introduction 14

Our seven compactness measures are as follows:


10/30

17 Introductio

Tis report is organized into fve color-coded chapters or each o

the fve Midwestern states oIllinois, Michigan, Minnesota, Ohio

and Wisconsin. An overview o the state is provided at the beginning

o each state chapter, along with a summary o the fndings rom the

mapping exercises. Te detailed mapping exercises are discussed in

three parts, one or congressional districts, one or the upper state

legislative chamber, and one or the lower legislative chamber. At the

beginning o each part, districts adopted or use during the 2000s

decade are described and the possibilities or maximizing the num-

ber o minority-majority districts are discussed. Tis is ollowed

with a discussion o the redistricting plans that are drawn under

each o our scenarios: grid, compact, minimization o county splits,

and minimization o census place splits. Please reer to the Introduc

tion or more details.

Number of majority-minority districts: Te Census Bureau reports the number o persons by race

and their Hispanic origin. Racial classifcations are complicated on the 2000 census because people

were permitted to identiy themselves by multiple racial categories. In addition to race, the Census

Bureau asks whether or not a person is o Hispanic origin. wo racial/ethnic categories are thus

defned. One is Arican-American, which includes any person who identifed themselves as

Arican-American alone or in combination with another racial or ethnic category. Te other is

Hispanic, which includes any person who identifed their ethnicity as Hispanic. It is important to

note that the two are not mutually exclusive, that is, some people identiy themselves as Hispanic

Arican-Americans.

Te average number o Arican-American and Hispanic majority districts are reported o across all

plans o a given plan type.

Political Composition: A districts partisan leaning is measured by the closely contested 2000

presidential election, which is the election most proximate to the post-2000 census redistricting in

these fve states. o measure the political composition o districts the presidential election results are

slightly modifed. Following standard practice among academics who study elections, minor party

candidate votes are actored out by calculating the two-party vote, the vote shares o the two major

political parties. Tis is not to say t hat these minor party candidates are unimportant, rather, in typi-

cal redistricting how districts are sculpted to avor major party candidates is most interesting.

Four types o districts are classifed:

Strong Republican is where the two-party vote is above 55% pro-Republican perormance.

Competitive Republican is where the two-party vote is between 50-55% pro-Republican perormance.

Competitive Democratic is where the two-party vote is between 50-55% pro-Democratic perormance.

Strong Democratic is where the two-party vote is above 55% pro-Democratic perormance.

Te breakpoints between sae and competitive districts are somewhat arbitrary. A competitive

district with 54.9% pro-Democratic perormance is only slightly more competitive than a strong

Democratic district with 55.1% pro-Democratic perormance. Furthermore, more accurately stating

districts competitiveness requires a statistical analysis o election results over a longer period o

time that is outside the scope o this project.

It is also important to note that district competitiveness is just one actor in an election outcome.

While the playing feld may be tilted towards one o the two candidates because o the relative

numbers o Democrats and Republicans within a district, the candidates campaigns also matter.Election winners are shaped by the presence o an incumbent, the experience o a challenger, money,

campaign message, national mood, scandal, and much more. A districts partisanship is simply one

among many actors that inuence election outcomes, but it is one o the ew t hat incumbents have

direct control over.

Te average number o sae and competitive Democratic and Republican districts are reported o

across all plans o a given plan type.

INRODUCION

Introduction 16


11/30

Illinois 18

Illinois Political Subdivisions

Kaskaskia, Illinois

Census Places Around Cook County

Te Land o Lincoln is located in the northern center o the

continental United States. Lake Michigan orms the border

along the states northeast corner. Wisconsin borders the state

to the north in a straight east-west line at 42 30 north latitude

established when the state was carved rom the Illinois erritory

in 1818 at the urgings o Nathaniel Pope, the Illinois erritory

delegate to the U.S. Congress. Previously, Illinois territorial

border established under the Northwest Ordinance o 1787

was approximately 30 miles southward and did not include

access to Lake Michigan, where present day Chicago is located.

Te Mississippi River constitutes the western border, the

Ohio River the southern border, and the Wabash River the

southern hal o the eastern border. Te northern hal o the

eastern border was fxed at 87 31 30 longitude when the

state o Illinois was ormed.

Political Subdivisions: Illinois has 102 counties. Te Census

Bureau, working with the state, defnes 1,313 census places,

which in Illinois are the cities, towns, villages, and, in a ew

cases, unincorporated communities that are thought to have

distinct identities. Tese range rom Kaskaskia, the smallest

with a 2000 census total population o nine persons. (Te village

o Ohlmans initial count o zero persons was later revised to

148.) Kaskaskia is the original capital o the Illinois erritory

and state o Illinois, beore the capital was moved to Vandalia in

1820. Te village was destroyed by an 1881 ood that carved a

new channel in the Mississippi River and placed Kaskaskia on the western bank o the Mississippi.

Tus, Kaskaskia is a part o Illinois located on the west bank o the Mississippi River. Kaskaskias

history illustrates that irregularly shaped waterways aect the states external and internal political

boundaries. For example, another major river o note that orms many county borders is the Illinois

River, which winds its way through the north central portion o the state rom Chicago to just north

o St. Louis.

Te largest census place in Illinois is Chicago, with a population o 2,896,016. O course, many

people live in the suburban cities nestled around Chicago. Te metropolitan area o Cook County,

the home o Chicago, together with the Collar Counties o DuPage, Kane, McHenry, and Will

contains 8,091,720 persons or 65% o the states entire population according to the 2000 census.

Te map o Cook County and its surrounding Collar Counties demonstrates how census places aredensely packed around the Chicago area. A close inspection also reveals how a number o these

census places straddle county lines. Districts that place a preerence on maintaining the integrity o

census place or county borders will thus necessarily have dierent confgurations.

Legend

Counties

Census places

Bodies of water

Illinois

19 Illino

Illinois Quick Facts

No. of Counties:

No. of Census Places:

Population 2000 Census

Total Population:

Non-Hispanic White:

% Non-Hispanic White

African-American:

% African-American

Hispanic:

(incl. Hispanic African-Amer% Hispanic

2000 Election Total Votes

George Bush:

Al Gore:

% Bush of Bush & Gore Vote

COOKDUPAGE

LAKE

WILL

KANE

WINNEBAGO MCHENRY

MADISON

ST. CLAIR

SANGAMON

PEORIA

CHAMPAIGN

MCLEAN

ROCK ISLAND

TAZEWELL

MACON

LA SALLE

KANKAKEE

DEKALB

VERMILION

ADAMS

WILLIAMSON

WHITESIDE

JACKSON

KNOX

KENDALL

COLES

OGLE

HENRY

MACOUPIN

STEPHENSON BOONE

MARION

JEFFERSON

LIVINGSTON

FRANKLIN

FULTON

GRUNDY

MORGAN

LEE

CLINTON

BUREAU

WOODFORD

CHRISTIAN

EFFINGHAM

RANDOLPH

MCDONOUGH

IROQUOIS

LOGAN

MONTGOMERY

MONROE

SALINE

PERRY

SHELBY

JO DAVIESS

FAYETTE

JERSEY

CRAWFORD

HANCOCK

DOUGLAS

EDGAR

WARREN

UNION

BOND

PIKE

WAYNE

CLARK

MERCER

DEWITT

CARROLL

PIATT

RICHLAND

MASON

LAWRENCE

WHITE

MASSAC

WASHINGTON

GREENE

CLAY

MOULTRIE

FORD

CASS

MARSHALL

WABASH

JOHNSON

MENARD

CUMBERLAND

JASPER

ALEXANDER

HAMILTON

HENDERSON

PULASKI

SCHUYLER

EDWARDS

BROWN

GALLATIN

STARK

PUTNAM

SCOTT

CALHOUN

HARDIN

POPE

Chicago

Rockford

Aurora

Peoria

Springfield

Joliet

Waukegan

Decatur

Champaign

Bloomington

Rock Island

East St. Louis


12/30

Illinois 20 21 Illino

Summary o est Redistricting Plans

In the test plans that ollow, Illinois redistricting is shown to be dominated by Chicago and its Collar Countie

where more than hal o the states population resides and where more than hal o the states districts be it

congressional or state legislative must be drawn. Te inner core o Chicago is heavily Democratic and the

metropolitan area becomes progressively more Republican in the surrounding suburbs.

Te high concentration o Democrats into urban Chicago means that Democrats are not ef ciently distribute

throughout the state or redistricting purposes. Even though Illinois voters cast more votes or Gore, Repub-

licans are markedly better than their statewide perormance in nearly all test plans. In some cases a majority

o the districts even avor Republicans. Plans that segregate the city o Chicago or Cook County in particular

overly concentrate Democrats into districts that they win overwhelmingly, while Republicans constitute a

narrow majority in a larger number o districts. For Democrats to receive a share o districts proportional to

their share o the statewide vote, districts need to cross Cook Countys lines to create more districts avorable

to Democrats.

Interestingly, the Republican advantage in redistricting is mitigated as districts become smaller. Tis is perhap

somewhat o a surprise since these smaller districts are less capable o addressing inef cient over-concentra-

tion o Democrats in the Chicago area by drawing districts that tie together the Democratic city core with

the Republican suburbs. For the legislative districts, particularly the House districts, the challenge to overall

representation reective o the state posed by the Chicago area can be oset by consolidating Downstate citie

into districts that avor Democrats. As a result, our test mapping o the House districts consistently best reec

the overall political composition o the state.

Te states minority populations are largely concentrated within the Chicago area, and while they are some-

what compact, they do not always neatly t into the most compact districts. Districts that do not explicitly

take race into account may produce some minority districts, but not as much as the 2000s plans that aspire to

promote racial representation. Our test plans suggest that ollowing these criteria examined here are insuf -

cient to adhere to ederal Voting Rights requirements.

Population: Te red scar in the upper right corner o the Illinois population density map represents

the high concentration o people living in Chicago and the Collar Counties. Notable mid-sized

larger cities and communities dot Downstate, too. For example, Peoria has 112,936 persons;

Springeld has 111,454 persons; Champaign/Urbana has 103,913; Decatur has 81,860; Rock Island

County with the city o the same name has 149,374; and the Counties o Madison and St. Clair

(which include the city o East St. Louis) have a combined total o 515,023 persons.

Te equal population requirement or legislative districts means that more than hal o t he states

districts must be located in and around the Chicago area, and about a h must be drawn around

the East St. Louis area. In both areas, small districts must be drawn in the urban interior and pro-

gressively larger districts must be drawn in the less densely populated suburban and outlying rural

areas. For the other mid-sized cities, the choice whether to consolidate these cities into one or more

urban districts or to split them among districts with an urban and rural mix may aect the character

o their representation and the overall balance o Democrats and Republicans in the congressional

delegation and state legislature.

Illinois is a racially mixed state. A little over two-thirds o the states population is non-Hispanic

White. Fieen percent o the states population is Arican-American and twelve percent is Hispanic.

Te states minority populations tend to be concentrated within urban areas, particularly Chicago

and East St. Louis. Tere are minority communities in the mid-sized cities and s cattered throughout

the rural areas, but according to the 2000 census, these communities tend to be too dispersed to

enable the drawing o minority-majority districts except in the East St. Louis area.

Politics: Illinois is divided like other states into Democratic urban areas and Republican rural areas.

Concentrations o Democrats Downstate, particularly in the mid-sized cities and in the East St.

Louis area, can support Democratic leaning districts. However, the partisan composition o the state

is dominated by the large number o Democrats living in Chicago and its environs. As a consequence,

Bush only received 43.8% o the combined Bush and Gore vote in 2000, the metric used to analyze

the partisan composition o districts in this report.

Perhaps surprisingly, Republicans enjoyed majority control o the state Senate during the 1990s, and

the state House until 1996. Redistricting is a key part o Republicans success in the 1990s. Republicans

drew state legislative lines in the 1990s and employed a strategy o splitting downstate cities and

drawing Republican leaning districts in the Collar Counties that took in just enough Democrats

to waste their votes in districts Republicans would win. Te Democrats controlled the process in

2000, and not surprisingly, devised state legislative plans with the opposite strategy in mind o

consolidating Downstate cities and splitting Republican areas to waste their votes. Democrats have

dominated the state legislature in the 2000s. Tus, as the shiing ortunes o the parties illustrate,

who draws the lines and how they are drawn can be an important actor in who controls the Illinoisstate government.

Illinois Population Density

Illinois Racial Diversity

Illinois Partisan Support

Less Dense

More Dense

Less

Minorities

More

Minorities

More

Bush Votes

More

Gore Votes

ILLINOIS


13/30

Illinois 22

Map Legend

District boundaries

Counties

Census places

Bodies of water

23 Illino

4th

Congressional 2000s Map

Congressional 2000s Map Chicago detail

Statistics

Statistics for 2000s Plan

Number of Districts: 19

County Splits: 49.0

Compactness Measures

Roeck: 0.335

Schwartzberg: 2.457

Total Perimeter: 6965.1

Polsby-Popper: 0.201

Population Polygon: 0.629

Population Circle: 0.382

Ehrenburg: 0.308

Racial Composition

African-American Majority Districts: 3

Hispanic Majority Districts: 1

Partisan Composition

Strong Republican: 7

Lean Republican: 2

Lean Democratic: 3

Strong Democratic: 7

Descriptions of map statistics provided on page 12.

15

17

7

4

ILLINOIS CONGRESS

Te Illinois constitution and state statutes are silent on the

congressional redistricting process and the criteria that should

be applied to drawing congressional districts. Te state thus

uses the regular legislative process the same process used to

create typical laws to draw congressional districts. Te state

ollows ederal criteria that congressional districts must be

single-member, o equal population, and adhere to the ederal

Voting Rights Act.

A divided state legislature elected in 2000 created the environ-

ment or a bipartisan compromise on redistricting. At the

time, Democrats controlled the st ate House, Republicans

controlled the state Senate, and Republican George Ryan was

governor. Te states loss o a congressional seat to reapportion-

ment urther complicated redistricting and likely meant two

incumbents would race of in a primary or general election.

Chicago area Rep. Rod Blagojevichs decision to run or

governor might have provided a compromise opportunity, but

the states population loss came rom Downstate, which meant

a congressional district must be collapsed in that region.

Rather than ace an uncertain court battle, then-Republican

U.S. House Speaker Dennis Hastert and Democratic Rep. Bill

Lipinski orged a bipartisan compromise.1 While congress

members do not play a ormal role in redistricting, states oen

adopt districts proposed by them.2 Tis compromise plan was

adopted by the state government.

Te plans contorted districts would warm the heart o Gov.

Elbridge Gerry, the namesake o the gerrymander. Republicans

had a perceived upper hand in negotiations because a ederal

court had chosen a Republican plan in the 1990s when the

divided state government deadlocked. Legislators anticipated

a similar outcome and believed another Republican riendly

court would draw districts i a compromise could not be

reached.3 Te heavy ax ell on Downstate Democratic Rep.

David Phelps. Te tornado-shaped 15th congressional district

on the states eastern edge was designed to deny him reelec-tion. Te end o the unnel touches down in Eldorado, where

Phelps home can be ound. o urthe r make it di cult or

him to move his residence into a riendlier district, much o

his then-current district was dismantled into three districts.

Te crab-shaped 17th district represented by Democrat Rep.

Lane Evans was congured to consolidate as many Downstate

Democrats as possible into a single district, urther hobbling

Phelps opportunities. Te southern pincer o the crab cuts

a block-wide path through parks and shopping malls in

Springeld to grab a minority community on the eastern edge

o town and union areas o Decatur to the east. Phelps moved

into the 19th congressional district, which comprised 34%

o his old district, to run against Republican incumbent Rep.

John Shimkus and lost.4

From aar, the 15th and 17th districts are two o the seemingly

most contorted congressional districts, but peering into

Chicago reveals the ear-muf shaped 4th congressional district

that is oen used as an example o gerrymandering. Tere is a

legitimate representational rational or this district, as it con-

nects together two Hispanic communities that are s eparated

by an Arican-American community located in the 7th dis-

trict. Te 4th congressional district was created in the 1990s by

a ederal court which ound that these Hispanic communities

merited an opportunity to elect a candidate o their choice per

Section 2 o the Voting Rights Act.5

American history is embedded in t his plan, too. Democratic

Representative Bobby Rush, representing the 1st congressional

district on Chicagos Southside, had his primary challenger in

the 2000 election removed rom the district. A young Illinois

state Senator named Barack Obama then decided to run or

U.S. Senate rather than challenge his new representative,

Democrat Jessie Jackson, Jr.. Obamas home was just a ew

blocks rom Rushs new district and he was just one among

three potential challengers who ound themselves removed

rom Rushs district.6

Given its irregularly-shaped districts, it is perhaps not surprising

that the redistricting plan splits 49 counties and scores low

on nearly all compactness measures. Tere are three Arican-

American majority districts and one Hispanic majority

district, all ound in the Chicago area. Surprisingly, in this

strongly Democratic state, Gore received a majority vote inonly ten o nineteen 2000s congressional districts, and was

represented by ten Republicans and nine Democrats in 2002,

the election ollowing the redistricting.7 Only ve o these

districts are within a competitive range: two Republican and

three Democratic.

Congressional 2000s Plan


14/30

Illinois 24

Map Legend

District boundaries

Counties

Census places

Bodies of water

25 Illino

Congressional Grid Test Map 1

Congressional Grid Test Map 2

Statistics

Averages for 3 Test Plans

No. of Districts: 19

County Splits: 54.0


Roeck: 0.517

Schwartzberg: 1.315





Ehrenburg: 0.534

Racial Composition

African-American Majority Districts: 1.3

Hispanic Majority Districts: 0.0


Strong Republican: 4.0

Lean Republican: 5.3

Lean Democratic: 2.7

Strong Democratic: 7.0


ILLINOIS CONGRESS

Tree grid plans are drawn where districts are designed to best

approximate squares. Each congressional district cannot have

the same uniorm square shape because the states borders are

not straight-edges. Te distribution o people across the state

urther challenges the drawing o straight lines. More districts

must be drawn within the densely populated Chicago area in

order to equalize districts population. Te state is also longer

in a north-south direction than it is wide in an east-west

direction, and in the Downstate region population is concen-

trated along the states western border, thereby requiring more

districts along the states Downstate western border.

Te two maps to the right illustrate two approaches to drawing

grid plans in Illinois. In the example map to the upper right,

the state is bisected down the middle, except or the northern-

most district. Te map on the lower right approaches the divi-

sion o the state by frst drawing a district that incorporates the

southern-most part o the state into a district and proceeds

northward. In both confgurations, note how the greater popu-

lation density in the western portion o Downstate permits

districts to be stacked one upon the other along the western

border, while the eastern districts south o Chicago must

encompass a larger area. In both examples, the eastern Down-

state districts tend to be longer in a north-south direction than

those to the west.

Te Chicago areas highest concentration o population along

Lake Michigan lends itsel to the ormation o three districts

stacked along the coast. Larger districts in the lesser, though

still highly populous, outlying suburbs ring these central city

districts. Tese outer districts cannot orm nicely-shaped

squares. Te map on the upper right tries to retain a square

shape or every district while the map below tries to create

more square shaped districts, while sacrifcing one districts

square shape by using it to accumulate leover pieces.

Compared to the 2000s plan, these grid plans have on averagea greater number o county splits than the plan employed in

the 2000s. Straight-edge census blocks that ollow armland

and east-west or north-south roads in t he Downstate region

are used as district borders. Tese roads tend to make straighter

district borders than the s ometimes-irregular county lines

composed o rivers. As might also be expected, these districts

score highly compact on multiple compactness measures and

are more compact than the 2000s plan.

Tese plans do not t ake into account the Voting Rights Act.

On average they have 1.3 Arican-American majority districts

and none had a Hispanic-majority district. Te minority

communities in the central Chicago area are large enough and

compact enough to draw at least one-Arican-American dis-

trict, but urther districts are limited. Arican-American com-

munities extend rom Southside Chicago, one to the northwest

and one to the southwest. Along Lake Michigans shore to the

north o Southside Chicago are Whites who live in high-rise

apartments. Tus, square districts that use Lake Michigan as

an eastern boundary will necessarily combine minority and

non-minority communities. Tese congressional grid plans

also ail to create a Hispanic-majority district because the

Hispanic communities are not as concentrated as the Arican-

American communities and thus some consideration o race

must enter into the drawing o a Hispanic-majority district.

Politically, these three grid plans look on average similar to

the 2000s plan. Tere are on average 9.7 Democratic and 9.3

Republican majority districts. A dierence emerges among the

districts in the competitive range. Where these grid plans have

an average o 8.0 competitive districts, 2.7 Democratic and 5.3

Republican, the 2000s plan only has 5 competitive districts,

3 Democratic and 2 Republican. Tese competitive numbers

help explain why despite being a heavily Democratic state the

Republicans have near parity in these grid plans. Democrats

are concentrated into the central Chicago area and congres-

sional districts that emphasize compact shapes, such as these

grid plans, concentrate Democrats into uncompetitive central

Chicago districts. Te remainder o the state has a more even

political balance, slightly tilting towards Republicans, which

overall results in a more e cient distri bution o Republicans

into districts across the state.

Congressional Grid


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Illinois 26

Map Legend

District boundaries

Counties

Census places

Bodies of water

27 Illino

Congressional Compact Test Map 1

Congressional Compact Test Map 2

Statistics



County Splits: 45.0


Roeck: 0.526

Schwartzberg: 1.362





Ehrenburg: 0.556

Racial Composition









ILLINOIS CONGRESS

Tree compact Illinois congressional plans are drawn, which

attempt, where possible, to draw districts that may be circular

or square, but are not constrained to all on a grid. In most

rural areas, Illinois county boundaries tend to orm straight

lines and even tend to do so or census blocks laid over the

armland. In Chicago, city blocks tend also to be straight-

edged as well, generally ollowing streets uninterrupted in

north-south and east-west directions. Tese grid-like patterns

aid drawing square districts. Circular districts, however, tend

to have ragged, pixilated edges because census blocks do not

have rounded borders, and thus surprisingly are poorly on

compactness measures that avor smaller district perimeters.

Te rounded path o the Mississippi River, combined with the

population center around East St. Louis, aids the drawing o cir-

cular congressional districts in this region. In the e xample map

to the upper right, there is a district with a core encompassing

Madison and St. Claire Counties. o the north, the Mississippi

River ortuitously bends westward with just enough space and

population to orm another circular-like district.

A good strategy could not be devised to draw circular districts

in the Chicago area. Te Lake Michigan coast ollows a nearly

straight line to the north-north-west and thus orms a regular

border that will necessarily cut any circular district. he

districts in the map to the lower right look similar to grid dis-

tricts, though the districts have been rearranged so that they

are more tightly packed together without generating as many

excess lefover pieces.

On average, these compact plans split 45 counties, which is

ewer than our grid plans and the 2000s plan. Cook County

and the Collar Counties must be split due to the numerous

districts that must be drawn in this region, so reductions in

county splits must be realized in Downstate districts. Tese

compact plans generally ollow county lines where they can,

though perhaps urther improvements in compactness could

have been realized by shaving some county corners.

On average, our compact plans had only one Arican-American

majority district and no Hispanic majority districts. As discussed

with regards to the grid plans, the minority population in

Chicago, while concentrated into the city core, is not arrayed

in a manner that acilitates their inclusion into more than

one district that maximizes compactness. Tis suggests that a

compactne ss standard is insu cient to satis y ederal Voting

Rights Act requirements.

Our three compact plans are, on average, politically similar to

our grid plans and the 2000s plan. Tere are on average 9.4

Democratic and 9.7 Republican majority districts. O these,

2.7 Democratic and 6.0 Republican districts are in a competi-

tive range. Te same dynamic aects the partisanship o the

grid and compact plans. Democrats are concentrated within

the Chicago regio n while Republicans are more e ciently

distributed Downstate to give them an advantage in redistrict-

ing over what might be expected given the states substantial

Democratic tendencies.

Congressional Compact


16/30

Illinois 28

Map Legend

District boundaries

Counties

Census places

Bodies of water

29 Illino

Congressional Minimize County Splits Test Map 1

Congressional Minimize County Splits Test Map 2

Statistics



County Splits: 14.0


Roeck: 0.425

Schwartzberg: 1.611





Ehrenburg: 0.416

Racial Composition









ILLINOIS CONGRESS

Tree congressional plans that minimize the number o county

splits are drawn. Such plans ofen present interesting puzzles

to solve since there are only a limited number o ways in

which districts can be congured such that they cross county

boundaries the ewest times possible. In a county such as

Cook where multiple districts may be drawn, districts are

generally drawn to be compact within the countys borders.

A place to begin solving this puzzle is to consider counties that

can hold one or more entire districts without crossing

the county line. Te ideal population or one o Illinois 19

congressional districts is 653,647 persons, which we permit

to deviate by 1% or 6,536 persons in our test plans. 8 Cook

Countys 5,376,741 persons supports 8.2 congressional

districts, which is just a little too much population to pack in 8

over-populated districts and retain a 1% population deviation.

Lake County, to the north o Cook County, has a population

o 644,356, which is just under the ideal population to sup-

port a single district within a 1% population deviation. Tus,

a natural division between these two counties is to cross the

county line once to round o the population o a Lake County

district. DuPage Countys population o 904,161 supports 1.4

districts and must be split. Te most logical choice is to round

o the population o a second district with Kane County to

the west, which has a population o 404,119. Te remaining

Kane County population can be combined with other counties

to orm another district.

Surprisingly, the remaining counties happen to have just the

right number o persons to draw the remaining districts in

the state without splitting another county. Indeed, as the two

maps to the right show, there are even dierent congurations

o Downstate districts that do not split another county.

Tere are an average o 0.7 Arican-American majority

districts and zero Hispanic districts among these three plans.

Minority communities extend slightly rom Cook County

into DuPage and Will Counties, thus minimizing county

splits does not necessarily place a constraint on the number

o minority districts. A conguration o eight Cook County

districts with the same number o minority-majority districts

as the 2000s plan, 3 Arican-American and 1 Hispanic, is

perhaps easible i a map drawer took race explicitly into

account in drawing internal Cook County districts, as may

be required by the ederal Voting Rights Act.

Tese plans that minimize the number o county splits are

slightly more avorable towards the Republicans than the

2000s plan and the grid and compact test plans. On average,

Republicans constitute a majority in 10.3 districts and Demo-

crats 8.7. Among these districts, 5.3 are Republican-leaning

competitive and 1.7 are Democratic-leaning competitive. In

these plans, the imperative to respect the boundaries o Cook

County even more strongly segregates Democrats into heavily

Democratic districts. In the remainder o the state, one o our

Downstate congurations split the concentration o Demo-

crats in the East St. Louis communities o Madison and St.

Clair Counties, resulting in one ewer Democratic district.

Te result rom respecting county lines is that Republicans are

more e ciently distributed into districts than the Democrats,

who nd many o their supporters clustered in heavily Demo-

cratic Chicago area districts.

Congressional Minimize County Splits


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Illinois 30

Map Legend

District boundaries

Counties

Census places

Bodies of water

31 Illino

Congressional Minimize Census Place Splits Test Map 1

Congressional Minimize Census Place Splits Test Map 2

Statistics



County Splits: 58.7


Roeck: 0.452

Schwartzberg: 1.795





Ehrenburg: 0.414

Racial Composition









ILLINOIS CONGRESS

Tree plans that minimize the number o split census places

are drawn, which are Census Bureau designations o city,

town, village, and other community borders created in con-

sultation with the Illinois state government. Te approach is

similar to our plans that minimize county splits, except that

the boundaries o the smaller census places are respected,

which sometimes even straddle county lines. Districts internal

to census places, such as Chicago, are generally drawn to be

compact within census places borders.

A major diference in the mapping approaches is evident in

the Chicago area. Te city o Chicagos population o 2,896,016

persons supports 4.4 congressional districts. Tus, at least

one district must straddle the citys border. Te many smaller

suburban cities ringing Chicago and pockets o unincorporated

county geography have just the right population to make it

possible to split only this one census place in the entire state.

Te map to the upper right demonstrates one such congurat

midwest mapping project il

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