Scales Used on Topographic Maps

Topographic Maps

Most USGS topographic maps use brown contours to show the shape and elevation of the terrain. Elevations are usually shown in feet, but on some maps they are in meters. Contour intervals vary, depending mainly on the scale of the map and type of terrain. The maps show and name prominent natural and cultural (manmade) features. Those at scales of 1:24,000 (1 inch = 2,000 feet) show an area in detail. Such detail is useful for engineering, local area planning, and similar purposes. Less detail is shown at scales of 1:50,000 (1 centimeter = 0.5 kilometer or 1 inch = 0.8 miles) to 1:100,000 (1 centimeter = 1 kilometer or 1 inch = 1.6 miles). They cover large areas and are used in land management and planning. Topo Map example

Area Featured

Most USGS map series divide the United States into quadrangles bounded by two parallels of latitude and two meridians of longitude. For example, a 7.5-minute map shows an area that spans 7.5 minutes of latitude and 7.5 of longitude, and it is usually named after the most prominent feature in the quadrangle. Others show a whole area--a county, state, national park, or place of special interest.

7.5-Minute Maps

The best known USGS maps are those of the 7.5-minute, 1:24,000-scale quadrangle series. On such maps, 1 inch = 2,000 feet. The area portrayed on each sheet ranges from 64 square miles at latitude 30 degrees north to 49 square miles at latitude 49 degrees north. The scale of the 7.5-minute map is used for areas where much detail must be shown. About 55,000 maps are needed to cover the entire United States excluding Alaska