ZIPFIP is a set of databases containing census and locational information organized by ZIP (ZIP code) and FIPS (county) levels and a program by which these databases may be accessed and manipulated. It has several useful features, including editing and displaying data, defining spatial boundaries known as market areas, determining distances between any two sites in the lower 48 States, and aggregating observations. ZIPFIP can _extract census information by county or ZIP code and correct information for missing values.