United States National Grid (Final Draft)

1 FGDC Document Number 2 3

NSDI

National Spatial Data Infrastructure

4 5 6 United States National Grid 7 (Final Draft) 8 9 10 11 Standards Working Group 12 Federal Geographic Data Committee 13 14 September, 2001 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

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

33 Federal Geographic Data Committee 34 35 Established by Office of Management and Budget Circular A-16, the Federal Geographic Data Committee 36 (FGDC) promotes the coordinated development, use, sharing, and dissemination of geographic data. 37 38 The FGDC is composed of representatives from the Departments of Agriculture, Commerce, Energy, 39 Housing and Urban Development, the Interior, State, and Transportation; the Environmental Protection 40 Agency; the Federal Emergency Management Agency; the Library of Congress; the National Aeronautics 41 and Space Administration; the National Archives and Records Administration; and the Tennessee Valley 42 Authority. Additional Federal agencies participate on FGDC subcommittees and working groups. The 43 Department of the Interior chairs the committee. 44 45 FGDC subcommittees work on issues related to data categories coordinated under the circular. 46 Subcommittees establish and implement standards for data content, quality, and transfer; encourage the 47 exchange of information and the transfer of data; and organize the collection of geographic data to reduce 48 duplication of effort. Working groups are established for issues that transcend data categories. 49 50 For more information about the committee, or to be added to the committee's newsletter mailing list, please 51 contact: 52 53 Federal Geographic Data Committee Secretariat 54 c/o U.S. Geological Survey 55 590 National Center 56 12201 Sunrise Valley Drive 57 Reston, Virginia 22092 58 59 Telephone: (703) 648-5514 60 Facsimile: (703) 648-5755 61 Internet (electronic mail): [email protected] 62 Anonymous FTP: www.fgdc.gov/pub/ 63 home page: www.fgdc.gov 64 65 The following is the recommended bibliographic citation for this publication: 66 67 United States National Grid (USNG), 68 FGDC, September 2001, Reston, Virginia.

ii Federal Geographic Data Committee XXX United States National Grid

69 70 CONTENTS 71 Page 72 1. Introduction...... 1 73 1.1 Objective...... 1 74 1.2 Scope ...... 2 75 1.3 Applicability ...... 2 76 1.4 Related Standards ...... 4 77 1.5 Standards Development Process...... 4 78 1.6 Maintenance Authority ...... 5 79 2. Conformance...... 6 80 3. Main Features and Specifications...... 7 81 3.1 Equivalency with MGRS ...... 7 82 3.2 Basic Numbering ...... 7 83 3.3 Referencing Scheme ...... 7 84 3.3.1.Grid Zone Designation ...... 7 85 3.3.2 100,000-meter Square Identification ...... 9 86 3.3.3 Grid Coordinates ...... 9 87 4. Relationship to Datums ...... 12 88 5. Accuracy and Precision...... 12 89 5.1 Accuracy...... 12 90 5.2 Precision ...... 12 91 5.2.1 Field Applications ...... 12 92 5.2.2 Special Applications...... 12 93 6. References...... 14 94 Annex A (Normative) Use of North American Datum 1927 (NAD 27)...... 15 95 Annex B (Normative) Truncation of UTM Coordinate Values...... 17 96 Annex C (Informative) USNG Implementations...... 19 97 C.1 Applications ...... 20 98 C.1.1 General Features ...... 20 99 C.1.2 Large Geographic Areas ...... 20 100 C.1.3 Regional Areas...... 20 101 C.1.4 Local Areas...... 21 102 C.1.5 Local Areas Near Grid Zone and/or 100,000-meter Square Boundaries ...... 21 103 C.1.6 Complete Grid Reference...... 21 104 C.1.7 Reading Grid Coordinates...... 24 105 Annex D (Informative) General Conventions for USNG...... 32 106 D.1 Appropriate Use of Truncated Values...... 33 107 D.2 Geographic Indexing...... 34 108 D.2.1 National Atlas or Map ...... 34 109 D.2.2 State Map Index...... 34 110 D.2.3 City Street Index...... 35 111 D.3 Portrayal of USNG Grids and Grid Values on Maps ...... 35 112 D.3.1 Grid Spacing...... 35 113 D.3.2 Grid Value Portrayal...... 37 114 D.3.3 Grid Reference Box...... 37 115 D.3.4 Map Legend Information...... 37 116 Annex E (Informative) USNG Standardized Numbering for NAD 27 Maps...... 39 117 Annex F (Informative) Glossary ...... 41 118 119

iii

Federal Geographic Data Committee XXX United States National Grid

119 Figures 120 Page 121 Figure 1 GZDs of the USNG ...... 8 122 Figure 2 Basic Plan of the 100,000-meter Square Identifications of the USNG...... 10 123 Figure 3 Organization of the USNG 100,000-meter squares ...... 11 124 Figure 4 Methods for showing GZDs and 100,000-meter Squares of the USNG in the 125 Grid Reference Box ...... 22 126 Figure 5 Sample Grid Reference Box with instructions for giving a complete reference ...... 23 127 Figure 6 USNG Principal Digits...... 25 128 Figure 7 Convention for portrayal of grid lines, UTM values, and single USNG 100,000-meter 129 Square Identification...... 26 130 Figure 8 Convention for portrayal of grid lines, UTM values, and multiple USNG 131 100,000-meter Square Identifications ...... 27 132 Figure 9 How to read USNG grid coordinates (1:24,000)...... 31 133 134 135 136 Tables 137 Table 1 Truncation of USNG Values...... 18 138 Table 2 Grid Spacing Recommendation ...... 36

Federal Geographic Data Committee XXX United States National Grid

139 1. INTRODUCTION 140

141 1.1 Objective 142 143 The objective of this standard is to create a more favorable environment for developing location-

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

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

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

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

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

149 reference system.

150

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Federal Geographic Data Committee XXX United States National Grid

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

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

168

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

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

171 its use within the NSDI.

172 173 1.2 Scope

174

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

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

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

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

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

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

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

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

183

184 1.3 Applicability

185

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

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

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

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

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

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

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

Federal Geographic Data Committee XXX United States National Grid

193

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

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

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

197 coordinates between databases or appliances.

198

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

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

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

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

203 option.

204

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

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

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

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

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

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

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

212 specialized uses.

213

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

215 during times of disaster relief operations.

216

217

Federal Geographic Data Committee XXX United States National Grid

217 1.4 Related Standards

218

219 This standard is compatible with:

220

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

222 Interchange, which standardizes representation of UTM coordinates for computer

223 representation.

224

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

226 GPS receiver and other positioning technologies.

227

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

229 schema for the description of coordinate reference systems.

230

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

232

233 1.5 Standards Development Process

234

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

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

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

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

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

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

241 was adopted.

242

Federal Geographic Data Committee XXX United States National Grid

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

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

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

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

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

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

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

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

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

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

253 FGDC standards directives.

254

255 1.6 Maintenance Authority

256

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

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

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

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

261

Federal Geographic Data Committee XXX United States National Grid

261 2. CONFORMANCE

262

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

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

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

266

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

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

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

270 map according to the guidance in this specification.

271

Federal Geographic Data Committee XXX United States National Grid

271 3. MAIN FEATUES AND SPECIFICATIONS.

272

273 3.1 Equivalency With MGRS

274

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

276 States including outlying territories and possessions.

277

278 3.2 Basic Numbering

279

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

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

282

283 3.3 Referencing Scheme

284

285 Numbering scheme shall be alphanumeric as follows:

286

287 3.3.1 Grid Zone Designation

288

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

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

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

292

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

294 taken from the global scheme of MGRS.

295

296 18S – Identifies a GZD.

Federal Geographic Data Committee XXX United States National Grid

180° Grid Zone Designation 18S 90°W Y Z 90°E 96° 90° 84° 54° 48° 42° 36° 66° 60° 78° 30° 24° 18° 72° 0° 180° 174° 168° 156° 150° 144° 138° 132° 126° 120° 102° 24° 30° 36° 42° 48° 54° 60° 66° 72° 108° 156° 162° 162° 114° 108° 18° 78° 84° 90° 96° 102° 114° 120° 126° 132° 138° 144° 150° 168° 174° 180° 84° 6° 0° 6° 12° X 12° 72° W 64° V 56° U 48° T 40° S 32° R 24° Q 16° P 8° N 0° M 8° L 16° K 24° J 32° H 40° G 48° F 56° E 64° D 72° C 12345678910111213141516171819202122232425262728293031 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 60 80° 0°

90°WA B 90°E

180°

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

297

Federal Geographic Data Committee XXX United States National Grid

298

299 3.3.2 100,000-meter Square Identification

300

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

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

303

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

305

306

307 3.3.3 Grid Coordinates

308

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

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

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

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

313 for E and N.

314 Examples:

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

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

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

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

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

Federal Geographic Data Committee XXX United States National Grid

180° 174° 168° 162° 24° AG ZG 24° HG JM RM SG WG XG YG BG CG DG EG FG GG KM LM MM NM PM QM TG UG VG ZF AF JL HF RL SF XF YF BF CF DF EF FF GF KL LL ML NL PL QL TF UF VF WF AE ZE HE JK RK SE UE VE WE XE YE BE CE DE EE FE GE KK LK MK NK PK QK TE AD ZD HD JJ RJ SD B VD WD XD YD D CD DD ED FD GD KJ LJ MJ NJ PJ QJ TD UD ZC AC JH HC RH SC XC YC BC CC DC EC FC GC KH LH MH NH PH QH TC UC VC WC AB ZB HB JG RG SB B B WB XB YB B CB DB EB FB GB KG LG MG NG PG QG TB UB V ZA AA JF RF SA HA WA XA YA BA CA DA EA FA KF LF MF NF PF QF TA UA VA 2,000,000m GA 2,000,000m AV ZV HV JE RE SV VV WV XVYV BV CV DV EV FV GV KE LE ME NE PE QE TV UV AU ZU HU JD RD SU XU YU BU CU DU EU FU GU KD LD MD ND PD QD TU UU VU WU 16° AT ZT 16° HT JC ST BT CT DT ET FT RC UT V T WT XT YT GT KC LC MC NC PC QC TT AS ZS HS JB RB SS XS YS BS CS DS ES FS GS KB LB MB NB PB QB TS US VS WS AR ZR HR JA RA SR XR YR BR CR DR ER FR GR KA LA MA NA PA QA TR UR VR WR ZQ AQ RV SQ BQ HQ JV XQ YQ CQ DQ EQ FQ GQ KV LV MV NV PV QV TQ UQ VQ WQ ZP AP JU RU SP CP DP HP VP WP XP YP BP EP FP GP KU LU MU NU PU QU TP UP

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

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

AL BL WL XL YL ZL CL DL EL FL GL HL JR KR LR MR NR PR QR RR SL TL UL VL 1,000,000m 1,000,000m AK BK K XK YK ZK CK DK EK FK GK HK JQ KQ LQ MQ NQ PQ QQ RQ SK TK UK VK W 8° 8° AJ BJ XJ YJ ZJ CJ DJ EJ FJ GJ HJ JP KP LP MP NP PP QP RP SJ TJ UJ VJ WJ

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

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

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

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

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

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

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

AA BA CA XA YA ZA DA EA FA GA HA JF RF SA TA UA VA WA 0m 0° KF LF MF NF PF QF 0° 0m 162° 180° 500,000m 174°500,000m 168° 500,000m False Easting False Easting False Easting Figure 2. Basic Plan of the 100,000-meter Square Identification of the United States National Grid (USNG) 320

Federal Geographic Data Committee XXX United States National Grid

SET 1 SET 2 SET 3 SET 4 SET 5 SET 6 ZONES 1, 7, 13, 19, 25, 31, 2, 8, 14, 20, 26, 32, 3, 9, 15, 21, 27, 33, 4, 10, 16, 22, 28, 34, 5, 11, 17, 23, 29, 35, 6, 12, 18, 24, 30, 36, 37, 43, 49, 55 38, 44, 50, 56 39, 45, 51, 57 40, 46, 52, 58 41, 47, 53, 59 42, 48, 54, 60 2,000,000 m

AV BV CV DV EV FV GV HV JE KE LE ME NE PE QE RE SV TV UV VV WV XV YV ZV AE BE CE DE EE FE GE HE JV KV LV MV NV PV QV RV SE TE UE VE WE XE YE ZE

AU BU CU DU EU FU GU HU JD KD LD MD ND PD QD RD SU TU UU VU WU XU YU ZU AD BD CD DD ED FD GD HD JU KU LU MU NU PU QU RU SD TD UD VD WD XD YD ZD

AT BT CT DT ET FT GT HT JC KC LC MC NC PC QC RC ST TT UT VT WT XT YT ZT AC BC CC DC EC FC GC HC JT KT LT MT NT PT QT RT SC TC UC VC WC XC YC ZC

AS BS CS DS ES FS GS HS JB KB LB MB NB PB QB RB SS TS US VS WS XS YS ZS AB BB CB DB EB FB GB HB JS KS LS MS NS PS QS RS SB TB UB VB WB XB YB ZB

1,500,000 m AR BR CR DR ER FR GR HR JA KA LA MA NA PA QA RA SR TR UR VR WR XR YR ZR AA BA CA DA EA FA GA HA JR KR LR MR NR PR QR RR SA TA UA VA WA XA YA ZA

AQ BQ CQ DQ EQ FQ GQ HQ JV KV LV MV NV PV QV RV SQ TQ UQ VQ WQ XQ YQ ZQ AV BV CV DV EV FV GV HV JQ KQ LQ MQ NQ PQ QQ RQ SV TV UV VV WV XV YV ZV

AP BP CP DP EP FP GP HP JU KU LU MU NU PU QU RU SP TP UP VP WP XP YP ZP AU BU CU DU EU FU GU HU JP KP LP MP NP PP QP RP SU TU UU VU WU XU YU ZU

AN BN CN DN EN FN GN HN JT KT LT MT NT PT QT RT SN TN UN VN WN XN YN ZN AT BT CT DT ET FT GT HT JN KN LN MN NN PN QN RN ST TT UT VT WT XT YT ZT

AM BM CM DM EM FM GM HM JS KS LS MS NS PS QS RS SM TM UM VM WM XM YM ZM AS BS CS DS ES FS GS HS JM KM LM MM NM PM QM RM SS TS US VS WS XS YS ZS

1,000,000 m AL BL CL DL EL FL GL HL JR KR LR MR NR PR QR RR SL TL UL VL WL XL YL ZL AR BR CR DR ER FR GR HR JL KL LL ML NL PL QL RL SR TR UR VR WR XR YR ZR

AK BK CK DK EK FK GK HK JQ KQ LQ MQ NQ PQ QQ RQ SK TK UK VK WK XK YK ZK AQ BQ CQ DQ EQ FQ GQ HQ JK KK LK MK NK PK QK RK SQ TQ UQ VQ WQ XQ YQ ZQ

AJ BJ CJ DJ EJ FJ GJ HJ JP KP LP MP NP PP QP RP SJ TJ UJ VJ WJ XJ YJ ZJ AP BP CP DP EP FP GP HP JJ KJ LJ MJ NJ PJ QJ RJ SP TP UP VP WP XP YP ZP

AH BH CH DH EH FH GH HH JN KN LN MN NN PN QN RN SH TH UH VH WH XH YH ZH AN BN CN DN EN FN GN HN JH KH LH MH NH PH QH RH SN TN UN VN WN XN YN ZN

AG BG CG DG EG FG GG HG JM KM LM MM NM PM QM RM SG TG UG VG WG XG YG ZG AM BM CM DM EM FM GM HM JG KG LG MG NG PG QG RG SM TM UM VM WM XM YM ZM

500,000 m AF BF CF DF EF FF GF HF JL KL LL ML NL PL QL RL SF TF UF VF WF XF YF ZF AL BL CL DL EL FL GL HL JF KF LF MF NF PF QF RF SL TL UL VL WL XL YL ZL

AE BE CE DE EE FE GE HE JK KK LK MK NK PK QK RK SE TE UE VE WE XE YE ZE AK BK CK DK EK FK GK HK JE KE LE ME NE PE QE RE SK TK UK VK WK XK YK ZK

AD BD CD DD ED FD GD HD JJ KJ LJ MJ NJ PJ QJ RJ SD TD UD VD WD XD YD ZD AJ BJ CJ DJ EJ FJ GJ HJ JD KD LD MD ND PD QD RD SJ TJ UJ VJ WJ XJ YJ ZJ

AC BC CC DC EC FC GC HC JH KH LH MH NH PH QH RH SC TC UC VC WC XC YC ZC AH BH CH DH EH FH GH HH JC KC LC MC NC PC QC RC SH TH UH VH WH XH YH ZH

AB BB CB DB EB FB GB HB JG KG LG MG NG PG QG RG SB TB UB VB WB XB YB ZB AG BG CG DG EG FG GG HG JB KB LB MB NB PB QB RB SG TG UG VG WG XG YG ZG

0 m AA BA CA DA EA FA GA HA JF KF LF MF NF PF QF RF SA TA UA VA WA XA YA ZA AF BF CF DF EF FF GF HF JA KA LA MA NA PA QA RA SF TF UF VF WF XF YF ZF 300,000 300,000 300,000 300,000 800,000 m 800,000 200,000 m 200,000 700,000 m 800,000 700,000 m 800,000 m 200,000 700,000 m 800,000 m 200,000 300,000 m 800,000 m 200,000 200,000 m 200,000 300,000 m 800,000 m 200,000 700,000 400,000 700,000 400,000 500,000 700,000 400,000 500,000 600,000 400,000 500,000 400,000 500,000 400,000 500,000 500,000 600,000 600,000 600,000 600,000 600,000

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

321

Federal Geographic Data Committee XXX United States National Grid

322 4. RELATIONSHIP TO DATUMS

323

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

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

326

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

328 27), see Annex A.

329

330 5. ACCURACY AND PRECISION

331

332 5.1 Accuracy

333

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

335

336 5.2 Precision

337

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

339 kilometers to one meter or higher.

340

341 5.2.1 Field Applications

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

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

344

345 5.2.2 Special Applications

346

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

348

Federal Geographic Data Committee XXX United States National Grid

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

350 NAD 83 datum.

351

352 General reference: 18SUJ23480647 – precision 10 meters.

353 Special application: 18SUJ2348316806479498 – precision 1 millimeter.

354

Federal Geographic Data Committee XXX United States National Grid

354 6. REFERENCES

355

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

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

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

359

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

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

362

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

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

365

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

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

367

368

369

370

371

372 United States National Grid

373 Annex A (Normative)

374 Use of North American Datum 1927 (NAD27)

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

375 ANNEX A (Normative)

376 Use of North American Datum 1927 (NAD 27)

377

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

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

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

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

382 point are designated 18SUJ23450626 (NAD 27).

383

384

385

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

386

387

388

389

390

391 United States National Grid

392 Annex B (Normative)

393 Truncation of USNG Coordinate Values

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

394 ANNEX B (Normative)

395 Truncation of USNG Coordinate Values

396

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

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

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

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

401 underlined for illustrative purposes.

402

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

Complete grid reference Truncated coordinates

Four digit Six digit Eight digit Ten digit

(1 km) (100 m) (10 m) (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

404

405

406

407

408

409 United States National Grid

410 Annex C (Informative)

411 USNG Implementations

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

412 ANNEX C (Informative)

413 USNG Implementations

414

415 C.1 Applications

416

417 C.1.1 General features

418

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

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

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

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

423

424 C.1.2 Large geographic areas

425

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

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

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

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

430

431 C.1.3 Regional areas

432

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

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

435

436

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

436 C.1.4 Local areas

437

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

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

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

441 required (such as 23480647).

442

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

444

445 C.1.5.1 Grid Zone Boundary

446

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

448 coordinate.

449

450 C.1.5.2 100,000-meter Square Boundary

451

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

453

454 C.1.6 Complete grid reference

455

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

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

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

459 grid reference.

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

U.S. National Grid U.S. National Grid U.S. National Grid

100,000-m Square ID 100,000-m Square ID 100,000-m Square ID 3 00 UJ UH TJ UJ 43 00 UH

Grid Zone Designation Grid Zone Designation Grid Zone Designation 18S 18S 18S

U.S. National Grid U.S. National Grid U.S. National Grid

100,000-m Square ID 100,000-m Square ID 3 00 100,000-m Square ID 4 00 TJ UJ UK UK VK 43 00

TH UH Grid Zone Designation Grid Zone Designation 18T 18T Grid Zone Designation 40°N 40°N 18S 18S 18S

U.S. National Grid U.S. National Grid U.S. National Grid 100,000-m Square ID 100,000-m Square ID 100,000-m Square ID QC TH HJ JD QE TK 23 00 78°W HH JC Grid Zone Designation Grid Zone Designation 156°W Grid Zone Designation 17T 18T 17S 18S 40°N 04Q 05Q 17S 18S 78°W 156°W 78°W

Figure 4. Methods for depicting Grid Zone Designations and 100,000-meter Square Identifications on the US National Grid in the Grid Reference Box. 460

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

1. Read numbers labeling the VERTICAL grid line left of point and estimate tenths (100 meters) from grid line to point. 93 Sample point 95 4 2. Read numbers labeling the HORIZONTAL grid line below point 92 and estimate tenths (100 meters) from grid line to point. 95 96 92 6 Example: 954926

100,000-m Square ID WHEN REPORTING ACROSS A 100,000 METER LINE, PREFIX THE 100,000 METER SQUARE IDENTIFICATION IN WHICH THE TH POINT LIES. Example: TH954926

Grid Zone Designation WHEN REPORTING OUTSIDE THE GRID ZONE DESIGNATION 18S AREA, PREFIX THE GRID ZONE DESIGNATION. Example: 18STH954926

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

462 C.1.7 Reading grid coordinates

463

464 C.1.7.1 Principal digits

465

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

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

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

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

470 Figures 6, 7 and 8 (pgs 25 – 27).

471

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

4293

4292000mN

94 295 96 297000mE

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 as long as at least one full set of UTM grid values are provided. (See Figure 7 for additional details.).

Figure 6. United States National Grid (USNG) Principal Digits. 472 25

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

12 313 314 315

95 95

4294 4294

4293 4293

92 4292000mN

U.S. National Grid 3 3 3 3 000m 12 13 14 15 E 100,000-m Square ID 1,000 meter US National Grid North American Datum 1983 Grid Zone Designation: 18S UH 100,000-m Square Identification: UH

Grid Zone Designation 18S

Figure 7. Convention for portrayal of grid lines, UTM values, and single USNG 100,000-meter Square Identification 473

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

TJ UJ 98 299 300 301

01 01

TJ TJ UJ UJ 4300 4300 TH TH UH UH

4299 4299

98 4298000mN

U.S. National Grid

100,000-m Square ID 3 00 2 2 3 3 000m 1,000 meter US National Grid 98 99 TH00 UH 01 E TJ UJ 43 00 North American Datum 1983 Grid Zone Designation: 18S TH UH

100,000-m Squares: TH, UH, TJ, UJ Grid Zone Designation 18S Figure 8. Convention for portrayal of grid lines, UTM values, and multiple USNG 100,000-meter Square Identifications 474

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

475 C.1.7.2 Read right and up

476

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

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

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

480

481 C.1.7.3 Read right

482

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

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

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

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

487

488 C.1.7.4 Read up

489

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

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

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

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

494

495 C.1.7.5 Grid coordinates

496

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

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

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

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

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

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

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

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

504

505 C.1.7.6 Example reading of grid coordinates

506

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

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

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

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

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

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

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

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

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

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

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

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

519

Full USNG: 18STH95419263

Without GZD: TH95419263

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

520

521

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

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

524 refinement.

525

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

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

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

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

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

530

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

4294 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 Grid: 18STH9541592635 preceding grid coordinates are the Grid Zone Designation, and 100,000-meter Square Identification (In this case 18S 18STH95419263 and TH respectively). These values are found in the Grid TH95419263 Reference Box in the map legend and are used as 95419263 appropriate to locate the feature within increasingly larger 954926 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. 410-meters 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. Grid: 9592 630-meters - 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: U.S. National Grid Bench Mark 324 94349341 100,000-m Square ID 3 00 Pond 94329206 TJ UJ Building 95649379 43 00 Road intersection 96189260 TH UH

Grid Zone Designation 18S Map extract from US Geological Survey 7.5-minute quadrangle FAIRFAX, VA, 1994 edition.

Figure 9. How to read United States National Grid (USNG) grid coordinates. 531 31

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

532

533

534

535

536

537 United States National Grid

538 Annex D (Informative)

539 General Conventions for the USNG

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

540 ANNEX D (Informative)

541 General Conventions for the USNG.

542

543 D.1 Appropriate use of truncated values

544

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

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

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

548 receiver or digital map. For example:

549

550 Department of Interior

551 1849 C Street NW, Washington, DC 20006

552 USNG: 18SUJ22850705

553

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

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

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

557

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

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

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

561 562 18S UJ 228070 563 or 564 18S UJ 2286 0705 565 566 This convention is most appropriate in hand written notes or GPS receiver equipment displays.

567

568

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

568 D.2 Geographic indexing

569

570 D.2.1 National Atlas or Map

571

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

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

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

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

576

577 Huntsville, AL ED 3743

578 Huntsville, AR VV 3393

579 Huntsville, MO WD 3965

580 Huntsville, OH KE 6280

581 Huntsville, TN GF 2532

582 Huntsville, TX TQ 5501

583 Huntsville, UT VL 3567

584

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

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

587

588 D.2.2 State map index

589

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

591

592 Huntington UQ 4961

593 Huntoon LF 5335

594 Huntsville TQ 5501

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

595 Huntsville St Park TP 5790

596 Hurlwood GT 7419

597

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

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

600

601 D.2.3 City street index

602

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

604

605 Baker TP 562995

606 Beto TP 571981

607 Bowers TQ 570005

608 Brook TP 567984

609 Bush TQ 543021

610

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

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

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

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

615

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

617

618 D.3.1 Grid spacing

619

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

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

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

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

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

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

625 side.

626 Table 2. Grid spacing recommendation

627

Map scale Grid spacing Grid spacing

(On ground in meters.) (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 20

or or

5,000 100.0

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

629 D.3.2 Grid value portrayal

630

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

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

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

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

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

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

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

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

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

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

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

642 the neatline.

643

644 D.3.3 Grid reference box

645

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

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

648

649 D.3.4 Map legend information.

650

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

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

653 - Datum to which grid is referenced.

654 - Grid Zone Designation data.

655 - 100,000-meter Square Identification data.

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

656

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

658

659 1,000-meter grid, US National Grid

660 North American Datum 1983

661 Grid Zone Designation: 18S

662 100,000-m Square Identification: UH

663

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

665

666 1,000-meter grid, US National Grid

667 North American Datum 1983

668 Grid Zone Designation: 18S

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

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

670 671

672

673

674

675

676 United States National Grid

677 Annex E (Informative)

678 USNG Standardized Numbering for NAD 27

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

679 ANNEX E

680 USNG Standardized Numbering for NAD 27 Maps

681

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

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

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

685 continue for some time.

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

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

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

690 ellipsoid for the USNG.

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

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

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

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

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

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

699 datum based UTM coordinates.

700 701 Example - The Washington Monument (USNG):

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

703 18S UJ 2345 0626 (NAD 27)

704

705

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

705

706

707

708

709

710

711

712

713

714 United States National Grid

715 Annex F (Informative)

716 Glossary

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

717 ANNEX F (Informative)

718 Glossary

719

720 ANSI American National Standards Institute

721 FGDC Federal Geographic Data Committee

722 GIS Geographic Information System

723 GPS Global Positioning System

724 GZD Grid Zone Designation

725 DMA Defense Mapping Agency

726 ISO International Organization for Standardization

727 MGRS Military Grid Reference System

728 NAD 27 North American Datum 1927

729 NAD 83 North American Datum 1983

730 NSDI National Spatial Data Infrastructure

731 NIMA National Imagery and Mapping Agency

732 PLSS Public Land Survey System

733 SPCS State Plane Coordinate System

734 UGRS Universal Grid Reference System

735 USNG United States National Grid

736 UTM Universal Transverse Mercator

737 WGS 84 World Geodetic System 1984