Mapping can be used in analyzing prospective sites for a prison location. This involves mapping vacant and useable land as possible sites for building, then adding filters of exclusions, i.e., terrain, prohibited land uses, lack of utilities, and lack of adequate transportation links. Mapping is also useful in making decisions about prison expansion, in that it shows where prisons are located in relation to where inmates resided prior to imprisonment, thus facilitating the location of new prisons in areas closer to where most inmates and their families live. Further, corrections mapping can be useful in situations in which contagious diseases are a problem. Mapping can trace the course of the disease through the prison system and provide information to prevent further contamination. In addition, GIS technology can be useful in working with individuals under community corrections supervision. Mapping technology can be used to examine the residential locations of parolees, so as to facilitate the efficient allocation of correctional and social services. Using GIS, an administrator can create a map that shows where offenders live and assign cases based on location. Mapping ensures that caseloads are assigned based on geographic location. Continuous monitoring of the location of probationers can be done through GPS, which is a navigation tool that allows users to determine their location anywhere in the world at any time of day. Other mapping uses pertain to locating halfway houses and determining geographic concentrations of offenders re-entering the community for the purpose of ensuring that needed services are provided in those areas. 25 references