A regional transit feasibility analysis and simulation tool (called RTFAST) can be used to analyze and simulate regional transit system performance. The growth of urban areas coupled with changes in socioeconomic and demographic patterns has resulted in the need to provide for mobility and accessibility in regional and multijurisdictional contexts. In this context, the ability to analyze, simulate, identify, and plan regional transit systems to best serve personal travel patterns is necessary. RTFAST has been developed within a geographic information system–based environment and effectively interfaced with existing travel-demand modeling systems. The capabilities of the tool were demonstrated, and sample results were obtained from its application in Florida.