Water Resources Division, U.S. Geological Survey 2000 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. application/pdf 10.3133/fs03800 en U.S. Geological Survey Map scales reports