Federal Geographic Data Committee

Department of Agriculture, Department of Commerce, Department of Defense, Department of Energy Department of Housing and Urban Development, Department of the Interior, Department of State

Department of Transportation, Environmental Protection Agency Federal Emergency Management Agency, Library of Congress

National Aeronautics and Space Administration, National Archives and Records Administration Tennessee Valley Authority

FGDC Document Number 1 2 3

4 5

United States National Grid 6

(Final Draft) 7

8

9

10

Standards Working Group 11 Federal Geographic Data Committee 12

13

September, 2001 14

15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

NSDI

National Spatial Data Infrastructure

NSDI

National Spatial Data Infrastructure

ii

Federal Geographic Data Committee 33 34 Established by Office of Management and Budget Circular A-16, the Federal Geographic Data Committee 35 (FGDC) promotes the coordinated development, use, sharing, and dissemination of geographic data. 36 37 The FGDC is composed of representatives from the Departments of Agriculture, Commerce, Energy, 38 Housing and Urban Development, the Interior, State, and Transportation; the Environmental Protection 39 Agency; the Federal Emergency Management Agency; the Library of Congress; the National Aeronautics 40 and Space Administration; the National Archives and Records Administration; and the Tennessee Valley 41 Authority. Additional Federal agencies participate on FGDC subcommittees and working groups. The 42 Department of the Interior chairs the committee. 43 44 FGDC subcommittees work on issues related to data categories coordinated under the circular. 45 Subcommittees establish and implement standards for data content, quality, and transfer; encourage the 46 exchange of information and the transfer of data; and organize the collection of geographic data to reduce 47 duplication of effort. Working groups are established for issues that transcend data categories. 48 49 For more information about the committee, or to be added to the committee’s newsletter mailing list, please 50 contact: 51 52

Federal Geographic Data Committee Secretariat 53 c/o U.S. Geological Survey 54

590 National Center 55 12201 Sunrise Valley Drive 56

Reston, Virginia 22092 57 58

Telephone: (703) 648-5514 59 Facsimile: (703) 648-5755 60

Internet (electronic mail): gdc@usgs.gov 61 Anonymous FTP: www.fgdc.gov/pub/ 62

home page: www.fgdc.gov 63 64 The following is the recommended bibliographic citation for this publication: 65 66 United States National Grid (USNG), 67 FGDC, September 2001, Reston, Virginia. 68

Federal Geographic Data Committee XXX United States National Grid

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69 CONTENTS 70

Page 71 1. Introduction................................................................................................................................................ 1 72

1.1 Objective.................................................................................................................................... 1 73 1.2 Scope ......................................................................................................................................... 2 74 1.3 Applicability .............................................................................................................................. 2 75 1.4 Related Standards ...................................................................................................................... 4 76 1.5 Standards Development Process ................................................................................................ 4 77 1.6 Maintenance Authority .............................................................................................................. 5 78

2. Conformance.............................................................................................................................................. 6 79 3. Main Features and Specifications............................................................................................................... 7 80

3.1 Equivalency with MGRS ........................................................................................................... 7 81 3.2 Basic Numbering ....................................................................................................................... 7 82 3.3 Referencing Scheme .................................................................................................................. 7 83

3.3.1.Grid Zone Designation ............................................................................................. 7 84 3.3.2 100,000-meter Square Identification ........................................................................ 9 85 3.3.3 Grid Coordinates ...................................................................................................... 9 86

4. Relationship to Datums .............................................................................................................................12 87 5. Accuracy and Precision.............................................................................................................................12 88

5.1 Accuracy...................................................................................................................................12 89 5.2 Precision ...................................................................................................................................12 90

5.2.1 Field Applications ...................................................................................................12 91 5.2.2 Special Applications................................................................................................12 92

6. References.................................................................................................................................................14 93 Annex A (Normative) Use of North American Datum 1927 (NAD 27)........................................................15 94 Annex B (Normative) Truncation of UTM Coordinate Values.....................................................................17 95 Annex C (Informative) USNG Implementations...........................................................................................19 96

C.1 Applications .............................................................................................................................20 97 C.1.1 General Features .....................................................................................................20 98 C.1.2 Large Geographic Areas .........................................................................................20 99 C.1.3 Regional Areas........................................................................................................20 100 C.1.4 Local Areas .............................................................................................................21 101 C.1.5 Local Areas Near Grid Zone and/or 100,000-meter Square Boundaries ................21 102 C.1.6 Complete Grid Reference........................................................................................21 103 C.1.7 Reading Grid Coordinates.......................................................................................24 104

Annex D (Informative) General Conventions for USNG..............................................................................32 105 D.1 Appropriate Use of Truncated Values......................................................................................33 106 D.2 Geographic Indexing................................................................................................................34 107

D.2.1 National Atlas or Map ............................................................................................34 108 D.2.2 State Map Index......................................................................................................34 109 D.2.3 City Street Index.....................................................................................................35 110

D.3 Portrayal of USNG Grids and Grid Values on Maps ...............................................................35 111 D.3.1 Grid Spacing...........................................................................................................35 112 D.3.2 Grid Value Portrayal...............................................................................................37 113 D.3.3 Grid Reference Box ................................................................................................37 114 D.3.4 Map Legend Information ........................................................................................37 115

Annex E (Informative) USNG Standardized Numbering for NAD 27 Maps................................................39 116 Annex F (Informative) Glossary ...................................................................................................................41 117 118

119

Federal Geographic Data Committee XXX United States National Grid

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Figures 119 Page 120

Figure 1 GZDs of the USNG .......................................................................................................... 8 121 Figure 2 Basic Plan of the 100,000-meter Square Identifications of the USNG............................10 122 Figure 3 Organization of the USNG 100,000-meter squares .........................................................11 123 Figure 4 Methods for showing GZDs and 100,000-meter Squares of the USNG in the 124

Grid Reference Box ........................................................................................................22 125 Figure 5 Sample Grid Reference Box with instructions for giving a complete reference ..............23 126 Figure 6 USNG Principal Digits ....................................................................................................25 127 Figure 7 Convention for portrayal of grid lines, UTM values, and single USNG 100,000-meter 128

Square Identification.......................................................................................................26 129 Figure 8 Convention for portrayal of grid lines, UTM values, and multiple USNG 130

100,000-meter Square Identifications .............................................................................27 131 Figure 9 How to read USNG grid coordinates (1:24,000) .............................................................31 132 133 134

135 Tables 136 Table 1 Truncation of USNG Values.............................................................................................18 137 Table 2 Grid Spacing Recommendation ........................................................................................36138

Federal Geographic Data Committee XXX United States National Grid

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1. INTRODUCTION 139 140

1.1 Objective 141 142

The objective of this standard is to create a more favorable environment for developing location-143

based services within the United States and to increase the interoperability of location services 144

appliances with printed map products by establishing a nationally consistent grid reference system 145

as the preferred grid for National Spatial Data Infrastructure (NSDI) applications. This standard 146

defines the US National Grid. The U.S. National Grid is based on universally defined coordinate 147

and grid systems and can, therefore, be easily extended for use world-wide as a universal grid 148

reference system. 149

150

There are a number of coordinate reference systems that can be used either in location service 151

appliances or on printed maps for the purpose of establishing a location. Within automated 152

location service appliances, the conversion of coordinates based on one well-defined reference 153

system to coordinates based on another can be both automatic and transparent to the user. These 154

devices can support multiple coordinate reference systems with little difficulty. However, it is not 155

easy for humans to work in multiple reference systems and humans cannot convert between 156

systems without the aid of location service appliances, calculators, or conversion tables. 157

Furthermore, it is difficult for humans to accurately determine a location coordinate from paper 158

maps when latitude and longitude are used because they do not appear square on the flat map. As a 159

consequence paper maps created for the general public frequently have a square reference grid that 160

overlays the non-rectangular coordinate reference system. It is computationally difficult, labor 161

intensive, and time consuming to convert the reference grid coordinate obtained from one printed 162

map to another printed map with a different grid even when both grid reference systems are well 163

defined. It can be impossible when proprietary grids are used. This situation greatly limits the 164

ability of humans to use location service devices with traditional printed maps. Subsequently, 165

Federal Geographic Data Committee XXX United States National Grid

2

location based services in this country have been limited to totally digital environments, restricting 166

the number of uses and retarding the development of the location based service industry. 167

168

This standard seeks to improve the current situation by identifying a single nationally consistent, 169

humanly facile grid reference system as the preferred U.S. National Grid (USNG) and promoting 170

its use within the NSDI. 171

172 1.2 Scope 173

174

This standard defines a preferred U.S. National Grid (USNG) for mapping applications at scales of 175

approximately 1:1,000,000 and larger. It defines how to present Universal Transverse Mercator 176

(UTM) coordinates at various levels of precision. It specifies the use of those coordinates with the 177

grid system defined by the Military Grid Reference System (MGRS). Additionally, it addresses 178

specific presentation issues such as grid spacing. The UTM coordinate representation, the MGRS 179

grid, and the specific grid presentation requirements together define the USNG. This standard is a 180

process standard as defined by the Federal Geographic Data Committee (FGDC) Standards 181

Reference Model. Specifically, it is a presentation process standard. 182

183

1.3 Applicability 184

185

This standard is for use in the acquisition or production, either directly or indirectly through 186

contracts and partnerships, of printed maps and the acquisition, either directly or indirectly, of 187

location service appliances. The USNG addresses the geospatial coordinate, human interface of 188

products and services designed as interoperable components of the NSDI. This standard applies to 189

printed maps that are intended to be used or are likely to be used by humans in conjunction with 190

location service appliances and to location service appliances that are intended to be used or are 191

likely to be used by humans in conjunction with printed map products. 192

Federal Geographic Data Committee XXX United States National Grid

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193

This standard is not primarily intended for the collection of geospatial data, either remote sensed 194

data collection or field surveys. Nor is it intended for internal data storage structure of any 195

Geographic Information System (GIS) or location service appliance or to the transfer of 196

coordinates between databases or appliances. 197

198

Use of USNG grid coordinates may be useful or even desirable within some systems or enterprises. 199

The decision to use USNG grid coordinates or some other coordinate system internal to 200

geographic information systems or location service appliances is left to the discretion of the system 201

developer as long as the human interface provides for USNG grid coordinate readout as one 202

option. 203

204

The USNG is not designed for surveying. This standard is not intended to replace the State Plane 205

Coordinate Systems (SPCS) established by the National Geodetic Survey. The SPCS is 206

specifically designed to meet the requirements of surveyors and engineers in determining location 207

and boundaries and some states mandate its use for specific purposes. SPCS coordinates can be 208

readily converted to USNG grid coordinates for subsequent use within the NSDI. The state plane 209

coordinate system (SPCS), Public Land Survey System (PLSS) and other accepted local spatial 210

reference systems may continue to be used where preferred for property descriptions and other 211

specialized uses. 212

213

The USNG is interoperable with the MGRS. This will be of critical importance to safety of life 214

during times of disaster relief operations. 215

216

217

Federal Geographic Data Committee XXX United States National Grid

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1.4 Related Standards 217

218

This standard is compatible with: 219

220

• ANSI X3.61-1986, Representation of Geographic Point Locations for Information 221

Interchange, which standardizes representation of UTM coordinates for computer 222

representation. 223

224

• ISO/DIS 19116, Positioning Services, which provides an interface for real-time output from a 225

GPS receiver and other positioning technologies. 226

227

• ISO/DIS 19111, Spatial Referencing by Geographic Coordinates, which provides a conceptual 228

schema for the description of coordinate reference systems. 229

230

• The USNG standard is based on the Military Grid Reference System 231

232

1.5 Standards Development Process 233

234

The USNG is an initiative of the Public XY Mapping Project, which is a not-for-profit 235

organization created specifically to promote the acceptance of a national grid for the United States. 236

The original concept can be traced to discussions within the American Society for Photogrammetry 237

and Remote Sensing. The Public XY Mapping Project developed the idea, conducting informal 238

tests and surveys to determine which coordinate reference system best met the requirements of 239

national consistency and ease of human use. Based on its findings, a standard based on the MGRS 240

was adopted. 241

242

Federal Geographic Data Committee XXX United States National Grid

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Because of the importance of this project to the NSDI, the Public XY Project brought its findings 243

to the FGDC in 1998. After briefing the FGDC Coordination Group, an ad hoc study group, that 244

included the FGDC Staff Director and the Chair of the FGDC Standards Working Group, 245

recommended that the FGDC accept the project as an FGDC standard development activity. The 246

FGDC Standards Working Group then created a subgroup led by the Public XY Mapping Project 247

to husband the project through the FGDC standards process. The subgroup contains members 248

from both the public and private sector, including key participation from the National Imagery and 249

Mapping Agency (NIMA) to assure that the USNG retains interoperability with the MGRS. The 250

subgroup refined the standard and through an iterative review process with the FGDC Standards 251

Working Group, produced, in November 2000, a final draft for public review consistent with the 252

FGDC standards directives. 253

254

1.6 Maintenance Authority 255

256

The Public XY Mapping Project will maintain this standard for the first five years. The Public XY 257

Mapping Project has demonstrated the ability to marshal the resources needed to develop, 258

promote, and initially implement the standard. After five years, the FGDC Standards Working 259

Group will evaluate the need to move maintenance responsibility to one of the FGDC agencies. 260

261

Federal Geographic Data Committee XXX United States National Grid

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2. CONFORMANCE 261

262

Location service appliances that claim conformance to this standard shall accept USNG 263

coordinates, as defined in Section 3, as input from the human user and provide USNG coordinate 264

output to the human user, as at least one option. 265

266

Printed map products that claim conformance to this standard shall provide a means for humans to 267

accurately locate a USNG coordinate on the map and for humans to extract, for any point on the 268

map, an accurate USNG coordinate. This will usually mean that the USNG will be printed on the 269

map according to the guidance in this specification. 270

271

Federal Geographic Data Committee XXX United States National Grid

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3. MAIN FEATUES AND SPECIFICATIONS. 271

272

3.1 Equivalency With MGRS 273

274

USNG coordinates shall be identical to the MGRS numbering scheme over all areas of the United 275

States including outlying territories and possessions. 276

277

3.2 Basic Numbering 278

279

USNG basic coordinate values and numbering are identical to UTM coordinate values over all 280

areas of the United States including outlying territories and possessions. 281

282

3.3 Referencing Scheme 283

284

Numbering scheme shall be alphanumeric as follows: 285

286

3.3.1 Grid Zone Designation 287

288

First, the U.S. geographic area shall be divided into 6-degree longitudinal zones designated by a 289

number and 8-degree latitudinal bands designated by a letter. Thus each area is given a unique 290

alphanumeric Grid Zone Designator (GZD) (Figure 1 – pg. 8). 291

292

The longitude zone numbers and latitude band letters for GZD over the United States shall be 293

taken from the global scheme of MGRS. 294

295

18S – Identifies a GZD. 296

Federal Geographic Data Committee XXX United States National Grid

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Figure 1. Grid Zone Designations of the U.S. National Grid (USNG)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60CDE

FG

HJ

KL

M

N

PQ

RS

T

U

V

W

X

80°72°

64°56°

48°

40°32°

24°

16°8°

0°

8°

16°24°

32°

40°48°56°

64°72°

84°

174°

180°

168°

162°

156°

150°

144°

138°

132°

126°

120°

114°

108°

102°

96°

90°

84°

78°

54°

48°

42°

36°

30°

24°

18°

0°12°

6° 6° 12°

18°

24°

30°

36°

42°

48°

54°

60°

66°

66°

72°

Grid Zone Designation 18S

174°

180°

168°

162°

156°

150°

144°

138°

132°

126°

120°

114°

108°

102°

96°

90°

84°

78°

72°

A B90°W 90°E

180°

0°

0°

Y Z

180°

90°E90°W

60°

297

Federal Geographic Data Committee XXX United States National Grid

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298

3.3.2 100,000-meter Square Identification 299

300

Each GZD 6x8 degree area shall be covered by a specific scheme of 100,000-meter squares where 301

a two-letter pair identifies each square (Figures 2 and 3 – pgs. 10 and 11). 302

303

18SUJ – Identifies a specific 100,000-meter square in the specified GZD. 304

305

306

3.3.3 Grid Coordinates 307

308

A point position within the 100,000-meter square shall be given by the UTM grid coordinates in 309

terms of its Easting (E) and Northing (N). For specific requirements or applications, the number of 310

digits will depend on the precision desired in position referencing. In this convention, the reading 311

shall be from left with Easting first, then Northing. An equal number of digits shall always be used 312

for E and N. 313

Examples: 314

18SUJ20 - Locates a point with a precision of 10 km 315

18SUJ2306 - Locates a point with a precision of 1 km 316

18SUJ234064 - Locates a point with a precision of 100 meters 317

18SUJ23480647 - Locates a point with a precision of 10 meters 318

18SUJ2348306479 - Locates a point with a precision of 1 meter 319

Federal Geographic Data Committee XXX United States National Grid

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Figure 2. Basic Plan of the 100,000-meter Square Identification of the United States National Grid (USNG)

BM CM DM EM FM GM

BL CL DL EL FL GL

BK CK DK EK FK GK

BJ CJ DJ EJ FJ GJ

BH CH DH EH FH GH

BG CG DG EG FG GG

BF CF DF EF FF GF

BE CE DE EE FE GE

BD CD DD ED FD GD

BC CC DC EC FC GC

BB CB DB EB FB GB

BA CA DA EA FA GA

BG CG DG EG FG GG

BF CF DF EF FF GF

BE CE DE EE FE GE

BD CD DD ED FD GD

BC CC DC EC FC GC

BB CB DB EB FB GB

BA CA DA EA FA GA

BV CV DV EV FV GV

BU CU DU EU FU GU

BT CT DT ET FT GT

BS CS DS ES FS GS

BR CR DR ER FR GR

BQ CQ DQ EQ FQ GQ

BP CP DP EP FP GP

BN CN DN EN FN GN

KM LM MM NM PM QM

KL LL ML NL PL QL

KK LK MK NK PK QK

KJ LJ MJ NJ PJ QJ

KH LH MH NH PH QH

KG LG MG NG PG QG

KF LF MF NF PF QF

KE LE ME NE PE QE

KD LD MD ND PD QD

KC LC MC NC PC QC

KB LB MB NB PB QB

KA LA MA NA PA QA

KV LV MV NV PV QV

KU LU MU NU PU QU

KT LT MT NT PT QT

KS LS MS NS PS QS

KR LR MR NR PR QR

KQ LQ MQ NQ PQ QQ

KP LP MP NP PP QP

KN LN MN NN PN QN

KM LM MM NM PM QM

KL LL ML NL PL QL

KK LK MK NK PK QK

KJ LJ MJ NJ PJ QJ

KH LH MH NH PH QH

KG LG MG NG PG QG

KF LF MF NF PF QF

TM UM VM WM XM YM

TL UL VL WL XL YL

TK UK VK WK XK YK

TJ UJ VJ WJ XJ YJ

TH UH VH WH XH YH

TG UG VG WG XG YG

TF UF VF WF XF YF

TE UE VE WE XE YE

TD UD VD WD XD YD

TC UC VC WC XC YC

TB UB VB WB XB YB

TA UA VA WA XA YA

TG UG VG WG XG YG

TF UF VF WF XF YF

TE UE VE WE XE YE

TD UD VD WD XD YD

TC UC VC WC XC YC

TB UB VB WB XB YB

TA UA VA WA XA YA

TV UV VV WV XV YV

TU UU VU WU XU YU

TT UT VT WT XT YT

TS US VS WS XS YS

TR UR VR WR XR YR

TQ UQ VQ WQ XQ YQ

TP UP VP WP XP YP

TN UN VN WN XN YN

AM

AL

AK

AJ

AH

AG

AF

AE

AD

AC

AB

AA

AG

AF

AE

AD

AC

AB

AA

AV

AU

AT

AS

AR

AQ

AP

AN

HM

HL

HK

HJ

HH

HG

HF

HE

HD

HC

HB

HA

HG

HF

HE

HD

HC

HB

HA

HV

HU

HT

HS

HR

HQ

HP

HN

JM

JL

JK

JJ

JH

JG

JF

JE

JD

JC

JB

JA

JV

JU

JT

JS

JR

JQ

JP

JN

JM

JL

JK

JJ

JH

JG

JF

RS

RR

RQ

RP

RN

RM

RL

RK

RJ

RH

RG

RF

RM

RL

RK

RJ

RH

RG

RF

RE

RD

RC

RB

RA

RV

RU

RT

SM

SL

SK

SJ

SH

SG

SF

SE

SD

SC

SB

SA

SG

SF

SE

SD

SC

SB

SA

SV

SU

ST

SS

SR

SQ

SP

SN

ZM

ZL

ZK

ZJ

ZH

ZG

ZF

ZE

ZD

ZC

ZB

ZA

ZG

ZF

ZE

ZD

ZC

ZB

ZA

ZV

ZU

ZT

ZS

ZR

ZQ

ZP

ZN

1,000,000m

8°

0°180° 500,000m

False Easting174° 168°

162°0°

8°

1,000,000m

2,000,000m2,000,000m

16°16°

24°162°168°174°180°

24°

0m 0m

500,000mFalse Easting

500,000mFalse Easting

320

Federal Geographic Data Committee XXX United States National Grid

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Figure 3. Organization of the U.S. National Grid (USNG) 100,000-meter Grid Squares

AV BV CV DV EV FV GV HV JE KE LE ME NE PE QE RE SV TV UV VV WV XV YV ZV

AU BU CU DU EU FU GU HU JD KD LD MD ND PD QD RD SU TU UU VU WU XU YU ZU

AT BT CT DT ET FT GT HT JC KC LC MC NC PC QC RC ST TT UT VT WT XT YT ZT

AS BS CS DS ES FS GS HS JB KB LB MB NB PB QB RB SS TS US VS WS XS YS ZS

AR BR CR DR ER FR GR HR JA KA LA MA NA PA QA RA SR TR UR VR WR XR YR ZR

AQ BQ CQ DQ EQ FQ GQ HQ JV KV LV MV NV PV QV RV SQ TQ UQ VQ WQ XQ YQ ZQ

AP BP CP DP EP FP GP HP JU KU LU MU NU PU QU RU SP TP UP VP WP XP YP ZP

AN BN CN DN EN FN GN HN JT KT LT MT NT PT QT RT SN TN UN VN WN XN YN ZN

AM BM CM DM EM FM GM HM JS KS LS MS NS PS QS RS SM TM UM VM WM XM YM ZM

AL BL CL DL EL FL GL HL JR KR LR MR NR PR QR RR SL TL UL VL WL XL YL ZL

AK BK CK DK EK FK GK HK JQ KQ LQ MQ NQ PQ QQ RQ SK TK UK VK WK XK YK ZK

AJ BJ CJ DJ EJ FJ GJ HJ JP KP LP MP NP PP QP RP SJ TJ UJ VJ WJ XJ YJ ZJ

AH BH CH DH EH FH GH HH JN KN LN MN NN PN QN RN SH TH UH VH WH XH YH ZH

AG BG CG DG EG FG GG HG JM KM LM MM NM PM QM RM SG TG UG VG WG XG YG ZG

AF BF CF DF EF FF GF HF JL KL LL ML NL PL QL RL SF TF UF VF WF XF YF ZF

AE BE CE DE EE FE GE HE JK KK LK MK NK PK QK RK SE TE UE VE WE XE YE ZE

AD BD CD DD ED FD GD HD JJ KJ LJ MJ NJ PJ QJ RJ SD TD UD VD WD XD YD ZD

AC BC CC DC EC FC GC HC JH KH LH MH NH PH QH RH SC TC UC VC WC XC YC ZC

AB BB CB DB EB FB GB HB JG KG LG MG NG PG QG RG SB TB UB VB WB XB YB ZB

AA BA CA DA EA FA GA HA JF KF LF MF NF PF QF RF SA TA UA VA WA XA YA ZA

AE BE CE DE EE FE GE HE JV KV LV MV NV PV QV RV SE TE UE VE WE XE YE ZE

AD BD CD DD ED FD GD HD JU KU LU MU NU PU QU RU SD TD UD VD WD XD YD ZD

AC BC CC DC EC FC GC HC JT KT LT MT NT PT QT RT SC TC UC VC WC XC YC ZC

AB BB CB DB EB FB GB HB JS KS LS MS NS PS QS RS SB TB UB VB WB XB YB ZB

AA BA CA DA EA FA GA HA JR KR LR MR NR PR QR RR SA TA UA VA WA XA YA ZA

AV BV CV DV EV FV GV HV JQ KQ LQ MQ NQ PQ QQ RQ SV TV UV VV WV XV YV ZV

AU BU CU DU EU FU GU HU JP KP LP MP NP PP QP RP SU TU UU VU WU XU YU ZU

AT BT CT DT ET FT GT HT JN KN LN MN NN PN QN RN ST TT UT VT WT XT YT ZT

AS BS CS DS ES FS GS HS JM KM LM MM NM PM QM RM SS TS US VS WS XS YS ZS

AR BR CR DR ER FR GR HR JL KL LL ML NL PL QL RL SR TR UR VR WR XR YR ZR

AQ BQ CQ DQ EQ FQ GQ HQ JK KK LK MK NK PK QK RK SQ TQ UQ VQ WQ XQ YQ ZQ

AP BP CP DP EP FP GP HP JJ KJ LJ MJ NJ PJ QJ RJ SP TP UP VP WP XP YP ZP

AN BN CN DN EN FN GN HN JH KH LH MH NH PH QH RH SN TN UN VN WN XN YN ZN

AM BM CM DM EM FM GM HM JG KG LG MG NG PG QG RG SM TM UM VM WM XM YM ZM

AL BL CL DL EL FL GL HL JF KF LF MF NF PF QF RF SL TL UL VL WL XL YL ZL

AK BK CK DK EK FK GK HK JE KE LE ME NE PE QE RE SK TK UK VK WK XK YK ZK

AJ BJ CJ DJ EJ FJ GJ HJ JD KD LD MD ND PD QD RD SJ TJ UJ VJ WJ XJ YJ ZJ

AH BH CH DH EH FH GH HH JC KC LC MC NC PC QC RC SH TH UH VH WH XH YH ZH

AG BG CG DG EG FG GG HG JB KB LB MB NB PB QB RB SG TG UG VG WG XG YG ZG

AF BF CF DF EF FF GF HF JA KA LA MA NA PA QA RA SF TF UF VF WF XF YF ZF

2,000,000 m

ZONES

1,000,000 m

500,000 m

0 m

1,500,000 m

SET 11, 7, 13, 19, 25, 31,

37, 43, 49, 55

SET 22, 8, 14, 20, 26, 32,

38, 44, 50, 56

200,

000

m

300,

000

400,

000

500,

000

600,

000

700,

000

800,

000

m

SET 33, 9, 15, 21, 27, 33,

39, 45, 51, 57

SET 44, 10, 16, 22, 28, 34,

40, 46, 52, 58

SET 55, 11, 17, 23, 29, 35,

41, 47, 53, 59

SET 66, 12, 18, 24, 30, 36,

42, 48, 54, 60

200,

000

m

300,

000

400,

000

500,

000

600,

000

700,

000

800,

000

m

200,

000

m

300,

000

400,

000

500,

000

600,

000

700,

000

800,

000

m

200,

000

m

300,

000

400,

000

500,

000

600,

000

700,

000

800,

000

m

200,

000

m

300,

000

400,

000

500,

000

600,

000

700,

000

800,

000

m

200,

000

m

300,

000

400,

000

500,

000

600,

000

700,

000

800,

000

m

321

Federal Geographic Data Committee XXX United States National Grid

12

4. RELATIONSHIP TO DATUMS 322

323

The standard datum for USNG coordinates shall be the North American Datum 1983 (NAD 83) or 324

its international equivalent, the World Geodetic System 1984 (WGS 84). 325

326

For practical applications using an existing map referenced to North American Datum 1927 (NAD 327

27), see Annex A. 328

329

5. ACCURACY AND PRECISION 330

331

5.1 Accuracy 332

333

Paper maps using the USNG grid shall conform to the National Map Accuracy Standard. 334

335

5.2 Precision 336

337

USNG provides a flexible numbering scheme to accommodate variable precision from tens of 338

kilometers to one meter or higher. 339

340

5.2.1 Field Applications 341

For general field applications, a precision of one hundred or ten meters will be typical. 342

For general applications, precision of up to one meter may be used. 343

344

5.2.2 Special Applications 345

346

For special applications, the USNG can provide precision greater than one meter. 347

348

Federal Geographic Data Committee XXX United States National Grid

13

For example, the location of the Washington Monument in Washington, DC can be identified on 349

NAD 83 datum. 350

351

General reference: 18SUJ23480647 – precision 10 meters. 352

Special application: 18SUJ2348316806479498 – precision 1 millimeter. 353

354

Federal Geographic Data Committee XXX United States National Grid

14

6. REFERENCES 354

355

American National Standards Institute, Inc. (ANSI), 1986, American National Standard for 356

Information Systems - X3.61-1986, Representation of Geographic Point Locations for Information 357

Interchange (Formerly Federal Information Processing Standard 70-1) 358

359

National Imagery and Mapping Agency (NIMA), 1990, DMA Technical Manual 8358.1 Datums, 360

Ellipsoids, Grids, and Grid Reference Systems, Edition 1 361

362

Synder, John P., 1987, Map Projections - A Working Manual; U.S. Geological Survey 363

Professional Paper 1395, US Government Printing Office, Washington, DC 364

365

Thompson, M.M., 1979, Maps for America, US Government Printing Office, Washington, DC366

Federal Geographic Data Committee XXX United States National Grid Annex A – Use of North American Datum 1927 (NAD 27)

15

367

368

369

370

371

United States National Grid 372

Annex A (Normative) 373

Use of North American Datum 1927 (NAD27)374

Federal Geographic Data Committee XXX United States National Grid Annex A – Use of North American Datum 1927 (NAD 27)

16

ANNEX A (Normative) 375

Use of North American Datum 1927 (NAD 27) 376

377

Published spatial references, such as a database or published list of spatial values for point 378

features, shall be referenced to NAD 83 whenever possible. When it is necessary to identify a 379

point on NAD 27, the coordinate values shall be followed by (NAD 27). For example, the NAD 83 380

coordinates of a point are designated 18SUJ23480647, while the NAD 27 coordinates of the same 381

point are designated 18SUJ23450626 (NAD 27). 382

383

384

385

Federal Geographic Data Committee XXX United States National Grid Annex B – Truncation of USNG Values

17

386

387

388

389

390

United States National Grid 391

Annex B (Normative) 392

Truncation of USNG Coordinate Values393

Federal Geographic Data Committee XXX United States National Grid Annex B – Truncation of USNG Values

18

ANNEX B (Normative) 394

Truncation of USNG Coordinate Values 395

396

A uniform system of truncation is adopted for the USNG1. Truncated coordinates begin with the 10,000-397

meter digit. Truncated coordinate values shall always consist of an even number of digits. Table 1 398

demonstrates how to truncate USNG grid coordinate values and compares these with truncated UTM grid 399

coordinates. The portions of the USNG grid coordinate that is imbedded in the UTM coordinate value are 400

underlined for illustrative purposes. 401

402

Table 1. Truncation of USNG values Examples of truncated grid coordinates 403

Truncated coordinates Complete grid reference

Four digit

(1 km)

Six digit

(100 m)

Eight digit

(10 m)

Ten digit

(1 m)

UTM +18,323483.168,4306479.498 2306 234064 23480647 2348306479

USNG 18SUJ2348306479 2306 234064 23480647 2348306479

404 1 A similar system of coordinate truncation can be employed for UTM grid coordinates. However, such a system of truncation is not part of the definition of the UTM system or the coordinate representation standard, ANSI X3.61, and is included here in Table 1 for illustration and uniformity purposes.

Federal Geographic Data Committee XXX United States National Grid Annex C – USNG Implementations

19

404

405

406

407

408

United States National Grid 409

Annex C (Informative) 410

USNG Implementations411

Federal Geographic Data Committee XXX United States National Grid Annex C – USNG Implementations

20

ANNEX C (Informative) 412

USNG Implementations 413

414

C.1 Applications 415

416

C.1.1 General features 417

418

All elements of a grid reference need not be used. Their use depends upon the size of the area of 419

activities, the type of use, and the scale of map to which the reference is keyed. Users will decide 420

which elements of the grid references are needed for specific circumstances. The following 421

paragraphs provide guidance for the use of GZDs and 100,000-meter Square Identifications. 422

423

C.1.2 Large geographic areas 424

425

For situations or issues spanning large geographical areas, such as conterminous United States or 426

Alaska, the GZD is usually given (such as 18S in 18SUJ23480647). The designation will alleviate 427

ambiguity between identical references that may occur when reporting to a station outside the area. 428

The GZD is always used in giving references on 1:1,000,000-scale to 1:500,000 scale maps. 429

430

C.1.3 Regional areas 431

432

For areas less than a grid zone wide, but exceeding 100,000 meters, only the 100,000-meter Square 433

Identification need be used (such as UJ in UJ23480647). 434

435

436

Federal Geographic Data Committee XXX United States National Grid Annex C – USNG Implementations

21

C.1.4 Local areas 436

437

For small and localized areas, the GZDs and 100,000-meter Square Identifications need not be 438

used, unless reporting falls within the parameters explained in following paragraphs. For an area 439

falling within a single 100,000-meter square, only the numerical part of the grid reference is 440

required (such as 23480647). 441

442

C.1.5 For local areas near Grid Zone and/or 100,000-meter Square boundaries 443

444

C.1.5.1 Grid Zone Boundary 445

446

In this case, GZD and 100,000-meter Square Identification have to be used with the USNG 447

coordinate. 448

449

C.1.5.2 100,000-meter Square Boundary 450

451

In this case, the 100,000-meter Square Identification has to be used with the USNG coordinate. 452

453

C.1.6 Complete grid reference 454

455

Topographic maps at 1:500,000 and larger scales should provide a grid reference box that contains 456

the elements for making a complete grid reference. See Figure 4 (pg. 22). Figure 5 (pg. 23) 457

provides an example of an option for a grid reference box with instructions for making a complete 458

grid reference. 459

Federal Geographic Data Committee XXX United States National Grid Annex C – USNG Implementations

22

Figure 4. Methods for depicting Grid Zone Designations and 100,000-meter Square Identificationson the US National Grid in the Grid Reference Box.

Grid Zone Designation18S

43 00

UH

UJ

100,000-m Square ID

U.S. National Grid

Grid Zone Designation18S

UH

100,000-m Square ID

U.S. National Grid

Grid Zone Designation18S

3 00

43 00

TH

TJ

UH

UJ

100,000-m Square ID

U.S. National Grid

UK

100,000-m Square ID

18S

Grid Zone Designation

18T40°N

U.S. National Grid

QC

100,000-m Square ID

TH

78°WGrid Zone Designation

17S 18S

78°W

U.S. National Grid

Grid Zone Designation18S

3 00

TJ UJ

100,000-m Square ID

U.S. National Grid

UK

Grid Zone Designation

18S

18T40°N

4 00

VK

100,000-m Square ID

U.S. National Grid

QE TK

100,000-m Square ID

Grid Zone Designation

17T 18T

78°W17S 18S

40°N

U.S. National GridU.S. National Grid

Grid Zone Designation

04Q 05Q

156°W

23 00HH

HJ

JC

JD

100,000-m Square ID

156°W

460

Federal Geographic Data Committee XXX United States National Grid Annex C – USNG Implementations

23

1. Read numbers labeling the VERTICAL grid line left of pointand estimate tenths (100 meters) from grid line to point.

2. Read numbers labeling the HORIZONTAL grid line below pointand estimate tenths (100 meters) from grid line to point.

95 4

92 6

WHEN REPORTING ACROSS A 100,000 METER LINE, PREFIXTHE 100,000 METER SQUARE IDENTIFICATION IN WHICH THE POINT LIES.

Example: 954926

Example: TH954926

WHEN REPORTING OUTSIDE THE GRID ZONE DESIGNATIONAREA, PREFIX THE GRID ZONE DESIGNATION.

Example: 18STH954926

Grid Zone Designation18S

100,000-m Square ID

Samplepoint

95 9692

93

TH

Figure 5. Sample Grid Reference Box with instructions for giving a complete reference.

461

Federal Geographic Data Committee XXX United States National Grid Annex C – USNG Implementations

24

C.1.7 Reading grid coordinates 462

463

C.1.7.1 Principal digits 464

465

The 10,000-meter and 1,000-meter digits are known as the principal digits and identify USNG grid 466

lines. Preceding and following UTM digits are shown as superscript. Alternatively, only the 467

principal digits for grid lines need be shown, but a sample full UTM value for both the Easting and 468

Northing axis must be depicted at least once on the map, usually near the southeast corner. See 469

Figures 6, 7 and 8 (pgs 25 – 27). 470

471

Federal Geographic Data Committee XXX United States National Grid Annex C – USNG Implementations

25

Figure 6. United States National Grid (USNG) Principal Digits.

The 10,000 and 1,000 meter values in UTM coordinates are known as the principal digits in USNG coordinates. In this illustration, six examples of Principal Digits have been circled. Note how the USNG principal digits are portrayed in larger type, and the preceding and post principal digit UTM values are included as superscript. This well established convention provides both USNG and UTM values in a manner that is easy to read and prevents confusion. Alternatively, grid lines may be identified by only the principal digits as seen in lines 96 and line 94 aslong as at least one full set of UTM grid values are provided. (See Figure 7 for additional details.).

29594

4292000mN

4293

94

96 297000mE

USNG Principal Digits

472

Federal Geographic Data Committee XXX United States National Grid Annex C – USNG Implementations

26

Figure 7. Convention for portrayal of grid lines, UTM values, and single USNG 100,000-meter Square Identification

1,000 meter US National GridNorth American Datum 1983Grid Zone Designation: 18S100,000-m Square Identification: UH

312 313 314 315000mE

92

4293

4294

95

4294

313

4293

95

12 314 315

4292000mN

Grid Zone Designation18S

UH

100,000-m Square ID

U.S. National Grid

473

Federal Geographic Data Committee XXX United States National Grid Annex C – USNG Implementations

27

298 299 300 301000mE

98

4299

4300

01

TH UH

UHTH

TJ UJ4300

299

4298000mN

4299

01

98 300 301

UH

UJ

UJTJ

TJ

TH

Figure 8. Convention for portrayal of grid lines, UTM values, and multiple USNG 100,000-meter Square Identifications

Grid Zone Designation18S

3 00

43 00

TH

TJ

UH

UJ

100,000-m Square ID

U.S. National Grid

1,000 meter US National GridNorth American Datum 1983Grid Zone Designation: 18S100,000-m Squares: TH, UH, TJ, UJ

474

Federal Geographic Data Committee XXX United States National Grid Annex C – USNG Implementations

28

C.1.7.2 Read right and up 475

476

The numerical part of a grid reference always contains an even number of digits. The first half of 477

the total number of digits represents the Easting, and the second half the Northing. The standard 478

convention of reading "right (Easting) and up (Northing)" is employed. 479

480

C.1.7.3 Read right 481

482

To read the Easting coordinate, locate the first Easting (vertical grid line to the left of the point of 483

reference and read the large digits, the principal digits labeling the line either in the top or bottom 484

margin or on the line itself. Smaller digits shown as part of a grid number are ignored. Estimate, 485

or scale the distance between the Easting line to the left of the point and the point itself. 486

487

C.1.7.4 Read up 488

489

The reading of the Northing coordinate is made in a similar manner. Locate the first Northing 490

(horizontal) grid line below the point of reference and read the principal digits labeling the line 491

located in the left or right margin or on the line itself. Then estimate, or scale the distance between 492

the Northing grid line below the point and the point itself. 493

494

C.1.7.5 Grid coordinates 495

496

The numerical part of a point reference taken from a 1,000-meter grid (on maps at scales of 497

1:100,000 and larger) is typically either a six-digit or eight-digit number; for example 234064 or 498

23480647. For a six-digit grid coordinate (i.e. 234064), reading from left to right, the 23 499

represents the 10,000 and 1,000 digits of the first Easting grid line to the left of the point, the 4 500

represents the estimated or scaled (nearest 100 meters) from the Easting line to the point, the 06 501

Federal Geographic Data Committee XXX United States National Grid Annex C – USNG Implementations

29

represents the 10,000 and 1,000 digits of the first Northing grid line below the point, and the 4 502

represents the estimated or scaled (nearest 100 meters) from the Northing grid line to the point. 503

504

C.1.7.6 Example reading of grid coordinates 505

506

Refer to Figure 9 (pg. 31) for the following example. 507

A USNG reference is formally written as an entity without spaces, parentheses, dashes, or decimal 508

points. In this example the grid coordinates are shown for a map feature, a small cemetery. From 509

the legend the feature is located in GZD (18S) and 100,000-meter square (TH). For the grid 510

coordinates, read right to the grid intersection immediately left of the place of interest. In Figure 9, 511

it is line 95. Then identify the grid line below the point (in this example 92). The coordinate value 512

9592 gives the location to within 1,000 meters. Measuring or estimating right in meters from line 513

95, finds the cemetery is another 415 meters. The complete USNG Easting component is 95415. 514

Measuring up (north) from line 92, the cemetery is another 635 meters. The complete USNG 515

Northing component is 92635. In this example a precision of 10 meters is required, thus the eight-516

digit coordinate value of the cemetery is 95419263. Notice how the 1-meter values of 5 have been 517

dropped in the eight-digit grid coordinates. The USNG coordinate values are: 518

519

Full USNG: 18STH95419263

Without GZD: TH95419263

Without GZD and 100,000-meter Square Identification: 95419263

520

521

Using the example of the cemetery above, grid coordinates are illustrated below for four, six, eight, 522

and ten digits. These values represent a point position (the southwest corner) for an area of 523

refinement. 524

525

Federal Geographic Data Committee XXX United States National Grid Annex C – USNG Implementations

30

Four digits 9592 Locating a point within a 1,000-meter square. 526

Six digits 954926 Locating a point within a 100-meter square. 527

Eight digits 95419263 Locating a point within a 10-meter square. 528

Ten digits 9541592635 Locating a point within a 1-meter square. 529

530

Federal Geographic Data Committee XXX United States National Grid Annex C – USNG Implementations

31

This figure illustrates how to obtain the spatial address for a feature on the map, in this case a cemetery. Coordinates are depicted as full and truncated values. Values preceding grid coordinates are the Grid Zone Designation, and 100,000-meter Square Identification (In this case 18S and TH respectively). These values are found in the Grid Reference Box in the map legend and are used as appropriate to locate the feature within increasingly larger areas. A full coordinate (i.e. 18STH95419263) provides a unique value over the entire world. TH95419263 provides a value with 10-meters precision out of a large, regional size area.

Finding 95419263. Think 9541 / 9263. - Reading right to grid line 95, measure right another 410-meters. Dropping the one-meter digit 0 produces the grid coordinate Easting value 9541. - Read up to grid line 92. Measure up another 630-meters. The Northing coordinate value is produced from grid line 92 + 630-meters (drop the 0) to make 9263. This makes the grid coordinate 95419263 (think 9541 / 9263).

Truncated examples:Feature: USNG Grid Coordinates:Bench Mark 324 94349341Pond 94329206Building 95649379Road intersection 96189260

Map extract from US Geological Survey7.5-minute quadrangle FAIRFAX, VA, 1994 edition.

Grid: 9592

410-meters

630-meters

Grid: 18STH954159263518STH95419263

TH9541926395419263

954926

Figure 9. How to read United States National Grid (USNG) grid coordinates.

4294

Grid Zone Designation18S

3 00

43 00

TH

TJ

UH

UJ

100,000-m Square ID

U.S. National Grid

531

Federal Geographic Data Committee XXX United States National Grid Annex D – General Conventions for the USNG

32

532

533

534

535

536

United States National Grid 537

Annex D (Informative) 538

General Conventions for the USNG539

Federal Geographic Data Committee XXX United States National Grid Annex D – General Conventions for the USNG

33

ANNEX D (Informative) 540

General Conventions for the USNG. 541

542

D.1 Appropriate use of truncated values 543

544

Full USNG values should be provided when they are used to indicate a geoaddress on stationary 545

letterhead, business cards, etc., even though the reader will know from the street address that it is 546

in the vicinity of a given town. This will facilitate someone using USNG geoaddresses with a GPS 547

receiver or digital map. For example: 548

549

Department of Interior 550

1849 C Street NW, Washington, DC 20006 551

USNG: 18SUJ22850705 552

553

Alternatively, when two people are exchanging positioning information by voice or other informal 554

means, they will often use only the USNG grid coordinate, such as: "We're located in Washington 555

at 1849 C Street, NW, grid 22850705." 556

557

A USNG spatial reference is formally written for general applications as an entity without spaces, 558

parentheses, dashes, or decimal points as depicted above. If users must break a spatial reference 559

into segments to facilitate reading, the following convention shall be used. 560

561 18S UJ 228070 562

or 563 18S UJ 2286 0705 564

565 This convention is most appropriate in hand written notes or GPS receiver equipment displays. 566

567

568

Federal Geographic Data Committee XXX United States National Grid Annex D – General Conventions for the USNG

34

D.2 Geographic indexing 568

569

D.2.1 National Atlas or Map 570

571

Features should be referenced in a map or atlas index using truncated USNG values because such 572

an index can then be used with any map conforming to this standard thus promoting 573

interoperability and the sharing of index information. In the case of an atlas, the particular page 574

numbers would also be indicated. For example, the cities of Huntsville can be referenced as: 575

576

Huntsville, AL ED 3743 577

Huntsville, AR VV 3393 578

Huntsville, MO WD 3965 579

Huntsville, OH KE 6280 580

Huntsville, TN GF 2532 581

Huntsville, TX TQ 5501 582

Huntsville, UT VL 3567 583

584

The exception to this format is Alaska, which exceeds 18° of latitude and longitude in extent (more 585

than three grid zones). For Alaska, the GZD should also be shown. 586

587

D.2.2 State map index 588

589

An index for a state atlas or map for Texas can reference cities as: 590

591

Huntington UQ 4961 592

Huntoon LF 5335 593

Huntsville TQ 5501 594

Federal Geographic Data Committee XXX United States National Grid Annex D – General Conventions for the USNG

35

Huntsville St Park TP 5790 595

Hurlwood GT 7419 596

597

In the case of a state atlas, the page numbers for each feature would also be indicated. The 598

exception to this format is again Alaska, where the GZD should also be shown. 599

600

D.2.3 City street index 601

602

A large-scale atlas or street map for Huntsville, TX can index street names as: 603

604

Baker TP 562995 605

Beto TP 571981 606

Bowers TQ 570005 607

Brook TP 567984 608

Bush TQ 543021 609

610

The coordinate values would usually be for the place where the street name appears on the map. 611

Note that since the extent of Huntsville, TX is not larger than 100 x 100 kilometers, the 100,000-612

meter Square Identifications are not essential in this street index. A city street atlas would also 613

reference the page number unique to that atlas for the street. 614

615

D.3 Portrayal of USNG grids and grid values on maps 616

617

D.3.1 Grid spacing 618

619

On large-scale paper maps, precise measurement requires a fine line square grid. Grids provide 620

the user with a geodetic reference in close proximity to any point on the map facilitating 621

Federal Geographic Data Committee XXX United States National Grid Annex D – General Conventions for the USNG

36

measurement and compensating for paper distortion. The size of grid squares is a trade off 622

between a precise reference and map clutter. Table 2 provides a proven and useful convention and 623

guide where grid squares on maps are no smaller than 20mm nor larger than 100mm along each 624

side. 625

Table 2. Grid spacing recommendation 626

627

Map scale Grid spacing

(On ground in meters.)

Grid spacing

(On map in millimeters.)

1:10,000 1,000 100

1:20,000 1,000 50.0

1:24,000 1,000 41.6

1:25,000 1,000 40.0

1:50,000 1,000

or

5,000

20

or

100.0

1:62,500 5,000 80.0

1:63,360 5,000 78.7

1:100,000 10,000 100.0

1:250,000 10,000 40.0

1:500,000 50,000 100.0

1:1,000,000 100,000 100.0

628

629

Federal Geographic Data Committee XXX United States National Grid Annex D – General Conventions for the USNG

37

D.3.2 Grid value portrayal 629

630

The USNG is based on the UTM grid, and as such the first two digits in USNG Easting and 631

Northing are the same as the 10,000-meter and 1,000-meter digits of UTM Easting and Northing 632

coordinates. Provisions should be made so map users can have essential information for 633

identifying the UTM coordinate equivalent of each USNG coordinate. A sample of at least one 634

full UTM value should be shown for both an Easting and Northing values, preferably in the lower 635

right corner of the map. When UTM values are shown, the principal digits are provided in larger 636

type. Other grid lines should be identified using UTM principal digits (both the 10,000-meter and 637

1,000-meter UTM values) with the proceeding digits as superscript. Alternatively, only the 638

principal digits for grid lines need be shown, but a sample full UTM value for both the Easting and 639

Northing axis must be depicted at least once on the map. Annex C, Figure 6, 7, and 8 (pgs. 25 – 640

27) depicts how grid lines are labeled and 100,000-meter squares identified on the map and along 641

the neatline. 642

643

D.3.3 Grid reference box 644

645

Maps at scales 1:500,000 and larger should provide a grid reference box with the content 646

illustrated in either Figure 4 or 5 (Annex C, pgs. 22 and 23) and similarly configured. 647

648

D.3.4 Map legend information. 649

650

Map legends should contain the following information regarding the grid; 651

- Size of grid squares and identify grid as US National Grid 652

- Datum to which grid is referenced. 653

- Grid Zone Designation data. 654

- 100,000-meter Square Identification data. 655

Federal Geographic Data Committee XXX United States National Grid Annex D – General Conventions for the USNG

38

656

Example for maps contained within a single 100,000-meter square: 657

658

1,000-meter grid, US National Grid 659

North American Datum 1983 660

Grid Zone Designation: 18S 661

100,000-m Square Identification: UH 662

663

Example for maps that cover two or more 100,000-m squares: 664

665

1,000-meter grid, US National Grid 666

North American Datum 1983 667

Grid Zone Designation: 18S 668

100,000-m Squares: TH, UH, TJ, UJ 669

Federal Geographic Data Committee XXX United States National Grid Annex E – USNG Standardized Numbering for NAD 27 Maps

39

670

671

672

673

674

675

United States National Grid 676

Annex E (Informative) 677

USNG Standardized Numbering for NAD 27 678

Federal Geographic Data Committee XXX United States National Grid Annex E – USNG Standardized Numbering for NAD 27 Maps

40

ANNEX E 679

USNG Standardized Numbering for NAD 27 Maps 680

681

Since the adoption of the NAD 83 as the U.S. national datum, there has been a sustained effort by federal 682

government mapping agencies to change national maps from the NAD 27 to the NAD 83 datum. However, 683

a substantial percentage of maps over the U.S. remain on the NAD 27 datum and that situation may 684

continue for some time. 685

686 The U.S. National Grid (USNG) numbering scheme for the 100,000-meter squares, is identical to the 687

Military Grid Reference System (MGRS) scheme for 100,000-meter squares designed for use with the WGS 688

84 over U.S. areas. This same numbering scheme shall also be used with the NAD 27 on the Clarke 1866 689

ellipsoid for the USNG. 690

691 By use of one single scheme (Figure 3 – pg. 11), the Grid Zone Designation and 100,000-meter Square 692

Identification will be the same for NAD 83 and NAD 27 datums. The ONLY difference will be in the two 693

UTM coordinates, which will be based on the geodetic coordinates as defined on their respective datums. 694

695 For example, the scheme for two adjacent 1: 24,000-scale quads within the same 100,000 meter square, 696

e.g., FALLS CHURCH, VA-MD (NAD 83) and WASHINGTON DC WEST, DC-MD-VA (NAD 27), 697

would portray the same 100,000-meter Square Identifications "UJ". The ONLY difference will be in the 698

datum based UTM coordinates. 699

700 Example - The Washington Monument (USNG): 701

18S UJ 2348 0647 [NAD 83 is implied] 702

18S UJ 2345 0626 (NAD 27) 703

704

705

Federal Geographic Data Committee XXX United States National Grid Annex F - Glossary

41

705

706

707

708

709

710

711

712

713

United States National Grid 714

Annex F (Informative) 715

Glossary716

Federal Geographic Data Committee XXX United States National Grid Annex F - Glossary

42

ANNEX F (Informative) 717

Glossary 718

719

ANSI American National Standards Institute 720

FGDC Federal Geographic Data Committee 721

GIS Geographic Information System 722

GPS Global Positioning System 723

GZD Grid Zone Designation 724

DMA Defense Mapping Agency 725

ISO International Organization for Standardization 726

MGRS Military Grid Reference System 727

NAD 27 North American Datum 1927 728

NAD 83 North American Datum 1983 729

NSDI National Spatial Data Infrastructure 730

NIMA National Imagery and Mapping Agency 731

PLSS Public Land Survey System 732

SPCS State Plane Coordinate System 733

UGRS Universal Grid Reference System 734

USNG United States National Grid 735

UTM Universal Transverse Mercator 736

WGS 84 World Geodetic System 1984 737