This synthesis will be of interest to transit practitioners and researchers, including technical staff and transit managers, as well as to vendors of Geographic Information System (GIS) solutions. This report illustrates the value of GIS to transit agencies in service provision and in potential cost savings. The synthesis summarizes the experiences of a variety of transit agencies, with information provided from small- and medium-sized transit operators, as well as from large transit agencies. It documents current practices, effective applications, and challenges.