The Massachusetts Bay Transportation Authority (MBTA) operates 152 bus routes in the Greater Boston area.

The MBTA operates a five-route bus rapid transit service branded as the Silver Line, as well as two limited-stop crosstown routes.

The MBTA has an active bus fleet around 1,040 buses with diesel-electric hybrid or compressed natural gas propulsion.

Over the next four decades under the BERy and Metropolitan Transit Authority (MTA), all but six streetcar routes were converted to bus or trolleybus.

A number of horsecar lines were built in Boston and surrounding towns in the second half of the 19th century, beginning with the Cambridge Railroad in 1856.

As that system was constructed in the first two decades of the 20th century, many streetcar lines were cut back from downtown Boston to rapid transit stations.

BERy bus service began on February 23, 1922, when buses replaced the North Beacon Street streetcar line.

[4] Initial bus routes largely replaced lightly-used streetcar lines or expanded service to new areas.

After being found unsuitable in 1965 for the Orange Line because it did not show up well on maps, yellow was chosen for the color of bus operations on January 8, 1972.

The MBTA took over the Eastern Massachusetts Street Railway in 1968, inheriting large networks based in Lynn and Quincy plus several lines in Norwood and Melrose.

The MBTA began subsidizing Middlesex and Boston Street Railway service based in Newton and Waltham in 1964, and took over the remaining routes in 1972.

[7] Three limited-stop crosstown routes were created in 1994 as a prelude to the Urban Ring Project, a never-implemented circumferential bus rapid transit (BRT) corridor.

[7] In 2017, the MBTA Board rejected a proposal to run all-night service on several routes with pulsed connections at a central hub.

[11][16] In 2022, the MBTA started cutting bus service due to a driver shortage resulting from a long-term retirement trend accelerated by the COVID-19 pandemic in Massachusetts.

Drivers were also unhappy about lack of access to bathrooms and "split shifts" with unpaid time between morning and evening rush hour that was too short to go home.

[1] The North Cambridge bus facility, which was used by trackless trolleys until March 2022, is to be modified for battery-electric buses.

Four suburban municipalities contract with outside operators for local circulator routes, most with partial MBTA subsidy.

[7] Most are run by private operators, except for the Beverly Shuttle, which is part of the Cape Ann Transportation Authority system.

[67] Center bus lanes are also funded for Lynnway in Lynn, and proposed for Blue Hill Avenue in Boston between Grove Hall and Mattapan.

[60][68][69][70][71] Additional lanes in Boston announced in 2020 but not yet implemented include Malcolm X Boulevard between Roxbury Crossing and Nubian Square, Warren Street between Nubian Square and Grove Hall, and Hyde Park Avenue between Forest Hills and Metropolitan Avenue.