Organizations that provide fixed-route mass transit services that utilize buses to transport people within the limits of a city, a metropolitan area, a county or a multicounty region or to move people from outlying areas into a city or metropolitan area. With traditional fixed-route services, buses run along an established path at preset times picking up passengers at designated bus stops. Variations include express fixed-route services with fewer stops; deviated-fixed route services which allow vehicles to deviate from the fixed route to pick up passengers at other specific locations, e.g., places of employment or child care centers, while keeping to a timetable for scheduled stops; point-deviation services which allow vehicles to stop at scheduled stops per a timetable but pick up passengers with advanced reservations between scheduled stops; and arrangements in which vehicles have no fixed stops but allow riders to hail a vehicle which travels along a fixed route and request a drop-off anywhere along the route.

Programs that provide door-to-door (or curb-to-curb) transportation for purposes of shopping, banking, social events, medical appointments, getting to and from work, and similar activities for people with disabilities who need special accommodations and are unable to utilize other available means of transportation. Also included are programs that provide transportation for youngsters with disabilities who have no other means of accessing necessary specialized services and activities. Some but not all vehicles used for this purpose are equipped with wheelchair lifts.

Programs that provide flexibly scheduled and routed door-to-door (or curb-to-curb) transportation services for the general public. Patrons generally have no private transportation and are unable to use the fixed-route public transportation system; or live in a rural area not served by a public transit system.