Bay Area Rapid Transit District
The San Francisco Bay Area Rapid Transit District was formed by the state legislature in 1957, comprising the counties of Alameda, Contra Costa, Marin, San Francisco, and San Mateo. Because Santa Clara County opted instead to first concentrate on its Expressway System, that county was not included in the original BART District. In 1959 a bill was passed in the state legislature that provided for the entire cost of construction of the tube to be paid for with surplus toll revenues from the San Francisco–Oakland Bay Bridge. This represented a significant portion of the total cost of the system.