The geographic base file uses computers to assist law enforcement agencies. It consists of a listing of streets and addresses to which have been added all necessary geocodes. It may be presented on paper, punch cards, computer tape, or computer disks. For law enforcement applications, the geographic base file must also index intersections to geographic areas. Other features, such as banks and freeways, may be represented on the file. Geocodes may include police beats, fire zones, city limits, and zip codes. Files may be structured according to street span, street segment, or individual address. Any information which has a street address may have geographic codes assigned to it, so that the information can be summarized by geographic area. The files can also be used for street network analysis to determine the shortest distance between two points. Applications to law enforcement activities include computer-assisted dispatching, crime prevention planning, crime analysis, resource allocation, investigative support, tactical deployment, traffic analysis, 911 emergency procedures, and automated vehicle monitoring. The automated geographic base file reduces errors through the use of machine coding techniques. The system is encouraged and supported by many Federal agencies. There are six programs available for creating local law enforcement geographic base files from existing files. These programs include intersect, polygon, reformat, strip dime, strip intersect, and tele dime. An appendix and several sketches are provided.