AC Transit (the Alameda-Contra Costa Transit District) is the transit agency providing bus service to western Alameda County and Contra Costa County, and has its headquarters in Oakland. It also provides transbay service to San Francisco.
AC Transit was created by voters in 1956, and initially financed by a 1959 bond measure which allowed AC Transit to buy out the remains of the Key System. 1,2 Service began in October, 1960. 1