Map Scale, Generalization, and Symbolization

Map scale expresses the ratio between a distance measured on the map and the corresponding true distance on the ground, and it can be stated in three interchangeable forms: a representative fraction such as 1:24,000, meaning one unit of map distance equals 24,000 of the same unit on the ground; a verbal statement such as "one inch equals two miles"; or a graphic bar scale that remains accurate even if the map image itself is later enlarged or reduced. The United States Geological Survey's classic 7.5-minute topographic quadrangle series, produced across the country from the mid-20th century onward, standardized on a scale of 1:24,000, a large enough scale to show individual buildings, roads, and contour lines at 20- or 40-foot intervals, in contrast to small-scale world atlas maps, on which a single centimeter may represent hundreds of kilometers and only the broadest features can be shown at all.