AC Transit is a regional bus agency serving parts of Alameda County and Contra Costa County in the western coastal area of the East Bay of the San Francisco Bay Area, headquartered in Oakland. In addition, AC Transit runs "transbay" routes across San Francisco Bay to the city of San Francisco, and selected areas in San Mateo County and Santa Clara County.AC Transit is constituted as a special district under California law. It is governed by seven elected members. It is not a part of or under the control of the Counties of Alameda or Contra Costa or any local jurisdictions.