The National Imagery and Mapping Agency (now known as the National Geospatial-Intelligence Agency) and equivalent agencies in Australia, Canada, and the United Kingdom collected data for the 1994 Digital
Chart of the World (DCW), which includes many data layers. The DCW was
designed for a wide range of military, scientific, and educational applications.
Included in the DCW is an urban areas layer, which shows areas of built-up
land where large populations exist. The U.S. Geological Survey compiled this map layer from the DCW urban areas information, with supplemental information from the National Atlas Cities and Towns map layer.
The Urban Areas of the United States map layer shows the built-up areas of the 50 United States. Military reservations are not included. Descriptive information includes the name of the urban area and codes identifying the State(s) in which the area falls.