AC Transit

AC Transit

Top left to bottom right: Local, Tempo, and Transbay buses, and Fruitvale station bus terminal
Founded	1960
Headquarters	1600 Franklin St, Oakland, CA
Locale	East Bay
Service area	Western Alameda and Contra Costa counties
Service type	Bus Bus rapid transit Paratransit Night bus
Routes	130[1]
Stops	approx. 5,500[1]
Fleet	630[1]
Daily ridership	159,500 (weekdays, Q4 2024)[2]
Annual ridership	40,609,500 (2024)[3]
Website	actransit.org

AC Transit is the main bus transit operator in the East Bay region of the San Francisco Bay Area, California. AC Transit is the third largest bus operator in California, serving the western portions of Alameda and Contra Costa counties, with a fleet of over 600 buses operating 130 routes.^[1] The agency was founded in 1960 as the successor of the bankrupt Key System.

AC Transit's primary services are its local bus routes, which serve the entire East Bay region from Richmond to Milpitas; "Transbay" regional routes, most of which operate between the East Bay and San Francisco via the Bay Bridge; and the Tempo bus rapid transit line from Oakland to San Leandro.

AC Transit has its headquarters in Oakland, with four bus operations facilities throughout the East Bay and a control center in Emeryville. The agency is officially known as the Alameda-Contra Costa Transit District, and it is structured as a special district governed by an elected seven-member board of directors. In 2024, AC Transit had a ridership of 40,609,500, or about 159,500 per weekday in the fourth quarter of 2024.