(CNN)Here's a look at the San Francisco Bay Area's rapid transit system, which is referred to as Bay Area Rapid Transit (BART).
Bay Area Rapid Transit Fast Facts
San Francisco Municipal Transportation Agency (SFMTA), which operates BART and the Municipal Railway system (MUNI), manages all forms of San Francisco area transportation and traffic, including streetcars, cable cars, bicycles, pedestrians, taxis and parking.
The BART system services Alameda County (Oakland), Contra Costa County, San Francisco County and stations in San Mateo County. A BART extension, in partnership with the Valley Transportation Authority, is planned to stretch into Silicon Valley/Santa Clara County (SVBX).
There are 669 revenue vehicles, or cars.
There are about 131 miles of BART track.
The trains travel at 70 mph maximum, 35 mph average and make 20-second station stops.
Weekday ridership is 414,166 trips on average.
BART has its own police force with 206 legally sworn-in law enforcement officers and 90 other staff members.
BART has a security system that includes alarms, video surveillance and other intrusion prevention equipment.
All BART frontline employees receive emergency response training.
BART supplies a mobile signal to customers of major wireless companies in most underground tunnels and stations.
BART does not run 24-hours per day.
MUNI covers about 49 square miles of the Bay area with more than 75 bus, light rail, trolley, streetcar and cable car lines. (source: SFMTA)
1912 - The San Francisco Municipal Railway system (MUNI) is established. It is one of the oldest transit systems in the world.
May 24, 1962 - Three northern California counties, Alameda, Contra Costa and San Francisco, adopt a plan to build a rapid transit system (BART) together. Originally Marin and San Mateo counties were to be part of the plan but they opted out.
June 19, 1964 - President Lyndon B. Johnson presides over the groundbreaking ceremony of the 4.4-mile test track between Concord and Walnut Creek.
November 1966-August 1969 - Construction of the Transbay Tube on the bottom of San Francisco Bay. The final cost of the tube is $180 million.
September 11, 1972 - The system opens to the public from Freemont to Oakland.
January 29, 1973 - The second leg of the system opens and extends from Oakland to Richmond.
May 21, 1973 - The Concord line opens.
November 3, 1973 - The San Francisco line opens.
1974 - Express bus service opens from Daly City to Belmont.
September 16, 1974 - Transbay Tube opens to the public.
March 10, 1975 - BART and MUNI begin a transfer system, cutting fares in half for BART/MUNI combinations riders.
May 3, 1983 - The AIRPORTER bus service begins shuttles from the Embarcadero station to San Francisco International Airport.
March 21, 1994 - BART's new operation center opens underneath the Lake Merritt Administration Building.
November 1999 - San Francisco Municipal Transportation Agency (SFMTA) is created when MUNI and the Department of Traffic are combined.
June 22, 2003 - BART officially opens a line to San Francisco International Airport.
June 25, 2006 - BART ridership surpasses 100 million - 100,128,800 for the 2006 fiscal year ending June 30.
January 1, 2009 - BART police officer Johannes Mehserle shoots and kills unarmed Oscar Grant III on a BART platform at the Fruitvale Station in Oakland. Officer Mehserle later resigns, and is subsequently arrested, tried and convicted of involuntary manslaughter. Mehserle is released from prison in June 2011.
July 3, 2011 - BART and Oakland police shoot and kill knife-wielding Charles Blair Hill at the civic Center Station in Oakland.
August 11, 2011 - BART cuts off wireless network service for three hours at several San Francisco stations to prevent coordinated protests of the shooting of Hill.
August 15, 2011 - "Flash mobs" close several BART stations for more than two hours in protest to BART shutting off wireless service.
August 18, 2011 - BART Police Officers Association website is hacked for the second time by the group Anonymous in retaliation for the wireless service shutdown of August 11. The group publishes the personal and home information of the police officers on the Internet.
August 22, 2011 - BART stations close as protestors demonstrate against the wireless service shutoff.
September 9, 2011 - Arrests are made and the Powell Street BART Station closes as protesters attempt to demonstrate.
2012 - BART orders 775 new cars to be built by Bombardier Transit Corporation.
July 1, 2013 - BART unions go on strike. The dispute centers on pay and benefits.
July 5, 2013 - Although contract negotiations are not finished, BART union workers end their strike and return to work.
October 18, 2013 - Union workers at BART go on strike.
October 19, 2013 - Two BART workers are killed by a train driven by an "operator trainee" during a strike.
October 21, 2013 - Union leaders and the management of BART come to an agreement to end a four-day strike.
April 17, 2014 - OSHA State regulators fine BART $210,000 for the safety violations that lead to the death of two BART workers in October of 2013.
August 28, 2014 - BART launches BART Watch, a mobile app that allows riders to report crimes and suspicious items or activities to BART Police.
November 22, 2014 - A monorail connecting Coliseum Station with Oakland International Airport begins operating.
June 24, 2015 - BART police adopt a new policy for interactions with transgender passengers, according to a statement on the BART website. The policy includes such guidelines as "if gender expression does not clearly indicate a transgender person's identity, an officer may politely and respectfully ask how the person wishes to be addressed.
March 15, 2016 - The first of 775 new rail cars arrives at BART's testing facility. The first in the new fleet will begin months of testing for safety, quality and integration before passengers ride in the new train car.
January 2018 - The first of 775 new train cars goes into service.
July 2018 - Three unrelated attacks occur within a five-day span at BART stations, leaving three people dead.