The demand for valid, timely, and detailed geographic data within local planning departments is increasing rapidly due to the increase in information required for planning, management, and decision making. Also, shrinking revenues increase the pressure on planning and development directors to produce such data from different sources in an efficient and effective manner (U.S. Department of Housing and Urban Development, 1968: Dueker, 1980; Teicholz and Berry, 1983; American Congress of Survey and Mapping [ACSM], 1989).
Geographic data represent geographic features such as points, lines, areas, andgrid cells and are linked with attribute data using one or more of the available geocoding (geographic coding! methods. Attribute data such as population, housing, transportation, land use, and many urban data files that include street addresses are linked (geocoded) with these geographic features for tabulation, mapping, and analysis. Street address data and automated street address geocoding systems are the focus of this study.
Automated street address geocoding systems are computerized information systems which assign geographic codes such as census tract numbers, city block numbers, or x,y coordinates to data records using street addresses as location identifiers. Street addresses are the linkages that tie data with geographic locations on maps. These geographic locations may take the form of areas such as census tracts, city blocks, or ownership parcels; the form of segments such as street segments or city block sides; or the form of points such as street intersections or facility locations. For years, data were geocoded manually. However, since computer systems evolved about four decades ago, the process of geocoding has increasingly been conducted automatically. A geocoding system requires at least three items: a map file, a data file, and a software program to perform the linkage.