At the regional level, transit market areas approximate the level of transit service an area can support. The concept was initially developed in 1996 Transit Redesign to provide general guidelines on the mix of transit services that may be appropriate for a given area. This guidance is provided for broad regional context; appropriate transit services are defined through professional transit service planning processes. The existing market area definitions identify five market areas, with Area I supporting the most intensive transit service and area 5 supporting the least intensive transit service. Transit Market Areas were first introduced in the 1996 Transit Redesign report produced by the Metropolitan Council. They have been updated periodically since then to better reflect census geography and demographic shifts and to refine the appropriate measures of transit supportiveness.The current Transit Market Areas, developed for the 2040 TPP update, are based on an index of population density, employment density, automobile availability (population over 16 less available automobiles), and intersection density (an indicator of urban form measured as a weighted count of intersections by block group).