The Massachusetts Bay Transportation Authority (MBTA) operates 152 bus routes in the Greater Boston area. The MBTA has a policy objective to provide transit service within walking distance for all residents living in areas with population densities greater than 5,000 inhabitants per square mile (1,900/km2) within the MBTA's service district. Much of this service is provided by bus. In 2023, the system had a ridership of 91,459,700, or about 303,300 per weekday as of the fourth quarter of 2023.

The Massachusetts Bay Transportation Authority 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, two light rail lines, and a five-line bus rapid transit system ; MBTA bus local and express service; the twelve-line MBTA Commuter Rail system, and several ferry routes. In 2023, the system had a ridership of 239,981,700, or about 755,500 per weekday as of the fourth quarter of 2023, of which the rapid transit lines averaged 267,100 and the light rail lines 80,300, making it the fourth-busiest rapid transit system and the third-busiest light rail system in the United States. As of the fourth quarter of 2023, average weekday ridership of the commuter rail system was 97,100, making it the fifth-busiest commuter rail system in the U.S.