The Universal Transverse Mercator (UTM) Grid

1 Map ProjectionsThe most convenient way to identifypoints on the curved surface of the Earthis with a system of reference lines calledparallels of latitude and meridians of lon-gitude. On some maps, the meridians andparallels appear as straight lines. On mostmodern maps, however, the meridians andparallels appear as curved lines. Thesedifferences are due to the mathematicaltreatment required to portray a curvedsurface on a flat surface so that importantproperties of the map (such as distanceand areal accuracy) are shown with mini-mum distortion. The system used to por-tray a part of the round Earth on a flatsurface is called a map simplify the use of maps and to avoidthe inconvenience of pinpointing loca-tions on curved reference lines, cartogra-phers superimpose on the map a rectangu-lar grid consisting of two sets of straight,parallel lines, uniformly spaced, each setperpendicular to the other.

2 This grid isdesigned so that any point on the map canbe designated by its latitude and longitudeor by its grid coordinates, and a referencein one system can be converted into a ref-erence in another system. Such grids areusually identified by the name of the par-ticular projection for which they Universal TransverseMercator GridThe National Imagery and MappingAgency (NIMA) (formerly the DefenseMapping Agency) adopted a special gridfor military use throughout the worldcalled the Universal Transverse Mercator (UTM) grid. In this grid, the world isdivided into 60 north-south zones, eachcovering a strip 6 wide in zones are numbered consecutivelybeginning with Zone 1, between 180 and174 west longitude, and progressing east-ward to Zone 60, between 174 and 180 east longitude. Thus, the conterminous 48 States are covered by 10 zones, fromZone 10 on the west coast through Zone19 in New England (fig.)

3 1). In each zone,coordinates are measured north and eastin meters. (One meter equals inch-es, or slightly more than 1 yard.) The nor-thing values are measured continuouslyfrom zero at the Equator, in a northerlydirection. To avoid negative numbers forlocations south of the Equator, NIMA scartographers assigned the Equator anarbitrary false northing value of10,000,000 meters. A central meridianthrough the middle of each 6 zone isassigned an easting value of 500,000meters. Grid values to the west of thiscentral meridian are less than 500,000; tothe east, more than 500, all NIMA-produced topographicmaps and many aeronautical charts showthe UTM grid lines. Determining a UTM Grid Value fora Map PointThe UTM grid is shown on all quadranglemaps prepared by the GeologicalSurvey (USGS). On quadran-gle maps (1:24,000 and 1:25,000 scale)and 15-minute quadrangle maps(1:50,000, 1:62,500, and standard-edition1:63,360 scales), the UTM grid lines areindicated at intervals of 1,000 meters,either by blue ticks in the margins of themap or with full grid lines.

4 The 1,000-meter value of the ticks is shown forevery tick or grid line. In addition, theactual meter value is shown for ticksnearest the southeast and northwest cor-ners of the map. Provisional maps at1:63,360 scale show full UTM grids at5,000-meter Universal Transverse Mercator (UTM) Grid10111213141516171819126 120 114 108 102 96 90 84 78 72 66 Figure 1. The Universal Transverse Mercator grid that covers the conterminous 48 United States comprises 10 zones from Zone 10 on the west coast through Zone 19 in New Department of the Geological SurveyUSGS Fact Sheet 077-01 August 2001To use the UTM grid, you can place atransparent grid overlay on the map tosubdivide the grid, or you can draw lineson the map connecting correspondingticks on opposite edges. The distances canbe measured in meters at the map scalebetween any map point and the nearestgrid lines to the south and west.

5 The nor-thing of the point is the value of the near-est grid line south of it plus its distancenorth of that line; its easting is the valueof the nearest grid line west of it plus itsdistance east of that line (see fig. 2). On maps at 1:100,000 and 1:250,000scale, a full UTM grid is shown at inter-vals of 10,000 meters and is numberedand used in the same information on these and other USGS products and services, call 1-888-ASK-USGS, use the faxservice, which is available 24 hours a dayat 703-648-4888, or visit the generalinterest publications Web site on map-ping, geography, and related topics additional information, visit Web site or the USGS homepage at 2. The grid value of line A-A is 357,000 meters east. The grid value of line B-B is 4,276,000 meters P is 800 meters east and 750 meters north of the grid lines; therefore, the grid coordinates of point P arenorth 4,276,750 and east 357,800.

6 BAAPB3554,2754,2764,2774,2783563573581,0 00 mNorthEast1,000 mx750800