Water Resources Division, U.S. Geological Survey 1999 Maps become out of date over time. Maps that are out of date, however, can be useful to historians, attorneys, environmentalists, genealogists, and others interested in researching the background of a particular area. Local historians can compare a series of maps of the same area compiled over a long period of time to learn how the area developed. A succession of such maps can provide a vivid picture of how a place changed over time. application/pdf 10.3133/fs15499 en Geological Survey (U.S.) Historical Mapping reports