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 131 miles of track, including a 9-mile (14 km) spur line running to Antioch, which uses diesel multiple unit vehicles, and a 3-mile (4.8 km) automated guideway transit line serving Oakland International Airport. With an average of 160,300 weekday passengers as of the second quarter of 2023 and 41,286,400 annual passengers in 2022, BART is the seventh-busiest heavy rail rapid transit system in the United States.