The increasing use of computers for storing and analyzing earth science information has sparked a growth in the demand for various types of cartographic data in digital form. The production of map data in computerized form is called digital cartography, and it involves the collection, storage, processing, analysis, and display of map data with the aid of computers. The U.S. Geological Survey, the Nation's largest earth science research agency, has expanded its national mapping program to incorporate operations associated with digital cartography, including the collection of planimetric, elevation, and geographic names information in digital form. This digital information is available for use in meeting the multipurpose needs and applications of the map user community.