Public transit service in Boston is provided by the Massachusetts Bay Transit Authority (MBTA). The MBTA was founded in 1964, succeeding the Metropolitan Transit Authority (MTA), established in 1947. The MTA had bought out the privately owned Boston Elevated Railway, which traced its own history back to 1887. Today, the MBTA operates a network of subways, streetcars, buses, trolleybuses, commuter rail trains, and ferries. It also holds several notable distinctions. The oldest subway line in the United States is operated by the MBTA, as the the tunnels used by the Green Line in downtown Boston were opened in 1897. The MBTA is the largest consumer of electricity and alternative fuels in all of Massachusetts. Finally, the MBTA is one of two transit systems to operate all five major types of terrestrial mass transit vehicles: regional (commuter) rail trains, “heavy” rapid transit (subway/elevated) trains, light rail vehicles (trolleys), electric trolleybuses, and motor buses. SEPTA in Philadelphia is the other.
The MBTA Red Line is the "youngest" of the four subway lines, as its first section was opened in 1912. Today, the Red Line operates from Alewife to Braintree and Ashmont. At Ashmont, passengers can connect to the Ashmont-Mattapan Line. While the Ashmont-Mattapan Line is shown on maps as being part of the Red Line, operationally it is considered to be part of the Green Line and for all intents and purposes is really its own line as opposed to being a part of either the Red or Green lines.
The Orange Line currently runs between Forest Hills and Oak Grove, offering connections to both Back Bay and North Station. The southern section of the line uses the Southwest Corridor that originally planned to be used as a right of way for I-95. On the northern section of the line, the newest MBTA station, Assembly, opened as an infill station on September 2, 2014.