The Massachusetts Bay Transportation Authority (abbreviated MBTA and known colloquially as "the T") is the public agency responsible for operating most public transportation services in Greater Boston, Massachusetts. The MBTA transit network includes the MBTA subway with three metro lines (the Blue, Orange, and Red lines), two light rail lines (the Green and Ashmont–Mattapan lines), and a five-line bus rapid transit system (the Silver Line); MBTA bus local and express service; the twelve-line MBTA Commuter Rail system, and several ferry routes. In , the system had a ridership of , or about per weekday as of , of which the rapid transit lines averaged and the light rail lines , making it the fourth-busiest rapid transit system and the third-busiest light rail system in the United States. As of , average weekday ridership of the commuter rail system was , making it the fifth-busiest commuter rail system in the U.S.
The MBTA is the successor of several previous pu