Over the last decade, police departments in the United States and elsewhere began to adopt geographic information systems (GIS) technology, recognizing the advantages of a system that enables the inspection of crime patterns and spatial filtering and querying, as well as more sophisticated analyses. If GIS is seen as a "primary" innovation in law enforcement, refinements in both visualization and geographic precision can be considered a secondary wave. In a case study in Baltimore County, Maryland, aerial photography and global positioning systems (GPS) were introduced and evaluated in an effort to develop an understanding of the possible benefits and limitations of the technologies. Incident street addresses geocoded in the usual manner were compared to coordinates obtained from a GPS instrument accurate to within a meter. Analysis suggests that locational errors were greater for some crime categories than for others. (Published Abstract) References