"Geographic information describes the locations, characteristics, and shapes of features and phenomena on the surface of the earth. Traditionally, such information has been produced, disseminated, and used in the form of paper maps and atlases, using various projections to allow the curved surface of the earth to be represented on flat paper...Today, vast amounts of geographic information are available for use in digital form, and a system that handles, processes, edits, manipulates, analyzes, and displays such data is a called a geographic information system (GIS)."
Geographic information system (gis). (2003). In E. D. Reilly, A. Ralston, & D. Hemmendinger (Eds.), Encyclopedia of computer science (4th ed.). Hoboken, NJ: Wiley.
Orthoimagery Data
USGS Structures Data
Regional and Local GIS data resource page