BART streaks along near Balboa Park in the southern part of San Francisco, 2011.

Photo: Chris Carlsson

The Bay Area Rapid Transit system, better known to all as BART, opened in 1972. It has its origins and precedents in mid-twentieth century Bay Area regional politics, and today is a workhorse of the Bay Area's public transit system, serving five counties after recent extensions into Santa Clara county and a generation ago into San Mateo county to reach the San Francisco airport.