Bay Area Rapid Transit
Bay Area Rapid Transit (BART) is a rapid transit system serving the San Francisco Bay Area in California. BART serves 50 stations along six routes and of track, including a spur line running to Antioch, which uses diesel multiple unit vehicles, and a automated guideway transit line serving Oakland International Airport. With an average of weekday passengers as of and annual passengers in , BART is the fifth-busiest heavy rail rapid transit system in the United States. BART is operated by the San Francisco Bay Area Rapid Transit District which formed in 1957. The initial system opened in stages from 1972 to 1974. The system has been extended several times, most recently in 2020, when Milpitas and Berryessa/North San José stations opened as part of the under construction Silicon Valley BART extension in partnership with the Santa Clara Valley Transportation Authority (VTA). BART serves large portions of its three member counties – San Francisco, Alameda, and Contra Costa – as well as smaller portions of San Mateo County and Santa Clara counties. The system has 50 stations: 22 in Alameda County, 12 in Contra Costa County, 8 in San Francisco, 6 in San Mateo County, and 2 in Santa Clara County. BART operates five named heavy rail services plus one separate automated guideway line. All of the heavy rail services run through Oakland, and all but the Orange Line cross the bay through the Transbay Tube to San Francisco. All five services run every day until 9 pm; only three services operate evenings after 9 pm. All stations are served during all service hours. The eastern segment of the (between Antioch and the transfer platform east of Pittsburg/Bay Point) uses different rolling stock and is separated from the rest of the line. Unlike most other rapid transit systems, BART lines historically were not primarily referred by shorthand designations such as color names (although the colors used on maps have been constant since 1980). The services are mainly identified on maps, schedules, and station signage by the names of their termini.
