To be most useful, a map must show

locations and distances accurately on

a 

sheet of paper of convenient size.

This means that all things included in

the map—ground area, rivers, lakes,

roads, distances between features,

and so on—must be shown

proportionately smaller than they

really are. The proportion chosen for

a particular map is its scale.

Large Is Small

Simply defined, scale is the

relationship between distance on the

map and distance on the ground. A

map scale might be given as a

drawing (a graphic scale), but usually

it is given as a fraction or a ratio—

1/10,000 or 1:10,000.

These "representative fraction" scales

mean that 1 unit of measurement on

the map—1 inch or 1 centimeter—

represents 10,000 of the same units

on the ground. If the scale were

1:63,360, for instance, then 1 inch on

the map would represent 63,360

inches or 1 mile on the ground

(63,360 inches divided by 12 inches

equals 5,280 feet or 1 mile). The first

number (map distance) is always 1.

The second number (ground

distance) is different for each scale;

the larger the second number is, the

smaller the scale of the map.

"The larger the number, the smaller

the scale" sounds confusing, but it is

easy to understand. A map of an area

100 miles long by 100 miles wide

drawn at a scale 

of 1:63,360 would be more than 8

feet square. To make the map a more

convenient size, either the scale used

or the area covered must be reduced.

If the scale is reduced to 1:316,800,

then 

1 inch on the map represents 5 miles

on the ground, and an area 100 miles

square can be mapped on a sheet

less than 2 feet square (100 miles at

5 miles to the inch equals 20 inches,

or 1.66 feet). On the other hand, if the

original 1:63,360 scale is used but the

mapped area is reduced to 20 miles

square, the resulting map will also be

less than 2 feet square.

Such maps would be easier to

handle. But would they be more

useful? In the small-scale map

(1:316,800), there is less room;

therefore, everything must be drawn

smaller, and some small streams,

roads, and landmarks must be left out

altogether. On the other hand, the

larger scale map (1:63,360) permits

more detail but covers much less

ground.

Many areas have been mapped at

different scales. The most important 

consideration in choosing a map is its

intended use. A town engineer, for

instance, may need a very detailed

map to locate precise sewers, power

and water lines, and streets. A

commonly used scale for this purpose

is 1:600 (1 inch on the map

represents 50 feet on the ground).

This scale is so large that many

features—such as buildings, roads,

and railroad tracks—that are usually

represented on smaller scale maps

by symbols can be drawn to scale.

U.S. Geological Survey Scales

The U.S. Geological Survey (USGS)

publishes maps at various scales.

The scale used for most United

States topographic mapping is

1:24,000. USGS maps at this scale

cover an area measuring 7.5 minutes

U.S. Department of the Interior

U.S. Geological Survey

Map Scales

USGS Fact Sheet 038-00

April 2000

1:20,000-scale map 1:63,360-scale map 1:500,000-scale map
of latitude and 7.5 minutes of

longitude and are commonly called

7.5-minute quadrangle maps. Map

coverage for most of the United

States has been completed at this

scale, except for Puerto Rico, which

is mapped at 1:20,000 and 1:30,000,

and for a few States that have been

mapped at 1:25,000. Most of Alaska

has been mapped at 1:63,360, with

some populated areas also mapped

at 1:24,000 and 1:25,000.

Maps at 1:24,000 scale are fairly

large and provide detailed information

about the features of an area,

including the locations of important

buildings and most campgrounds, ski

lifts, and water mills. Footbridges,

drawbridges, fence lines, and private

roads are also shown at this scale.

Usually these features are omitted

from maps in the 1:50,000- to

1:100,000-scale range; these maps

cover more area while retaining a

reasonable level of detail. Maps at

these scales are most often produced

using the 30- by 60-minute

quadrangle formats.

Small-scale maps (1:250,000 and

smaller) show large areas on single

map sheets, 

but details are limited to major

features, such as boundaries, parks,

airports, major roads, railroads, and

streams.

Information

The table below shows information

about maps available from the USGS.

1:24,000-scale map 1:100,000-scale map 1:250,000-scale map

Puerto Rico 7.5 minute 1:20,000 1,667 feet 200 meters 7.5 by 7.5 minute 71

7.5 minute 1:24,000 2,000 feet (exact) 240 meters 7.5 by 7.5 minute 49 to 70

7.5 minute 1:25,000 2,083 feet 250 meters 7.5 by 7.5 minute 49 to 70 

7.5 by 15 minute 1:25,000 2,083 feet 250 meters 7.5 by 15 minute 98 to 140

USGS-DMA 15 minute 1:50,000 4,166 feet 500 meters 15 by 15 minute 197 to 282

15 minute* 1:62,500 1 mile 625 meters 15 by 15 minute 197 to 282

Alaska Maps 1:63,360 1 mile (exact) 633.6 meters 15 by 20 to 36 minute 207 to 281

County Maps 1:50,000 4,166 feet 500 meters County area Varies

County Maps 1:100,000 1.6 miles 1 kilometer County area Varies

30 by 60 minute 1:100,000 1.6 miles 1 kilometer 30 by 60 minute 1,568 to 2,240

30 minute* 1:125,000 2 miles 1.25 kilometers 30 by 30 minute 786 to 1,124

1 degree by 2 degree or 3 degree 1:250,000 4 miles 2.5 kilometers 1° by 2° or 3° 4,580 to 8,669

State Maps 1:500,000 8 miles 5 kilometers State area Varies

State Maps 1:1,000,000 16 miles 10 kilometers State area Varies

U.S. Sectional Maps 1:2,000,000 32 miles 20 kilometers State groups Varies

Antarctica Maps 1:250,000 4 miles 2.5 kilometers 1° by 3° to 15° 4,089 to 8,336

Antarctica Maps 1:500,000 8 miles 5 kilometers 2° by 7.5° 28,174 to 30,462

* Abandoned map series, but still available for ordering.

USGS Maps

Standard Quadrangle

1 inch represents 1 centimeter quadrangle size area

Series Scale approximately represents (latitude by longitude) (square miles)