Bus system serving the Boston metropolitan area operated by the MBTA
Massachusetts Bay Transportation Authority bus system| Company type | Public transit agency |
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| Industry | Public transportation |
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| Headquarters | Boston , United States |
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Area served | Boston metropolitan region |
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| Products | Bus services, including Silver Line bus rapid transit |
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| Owner | Massachusetts Bay Transportation Authority (MBTA) |
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| Website | www.mbta.com |
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The Massachusetts Bay Transportation Authority (MBTA) bus system manages 151 routes throughout the Boston metropolitan region. Every route provides connections to the MBTA subway, Commuter Rail, or other bus lines. Most of these routes have origins in historic streetcar operations once run by the Boston Elevated Railway and suburban firms like the Eastern Massachusetts Street Railway. The MBTA directly controls 147 of these routes, while four are operated by private contractors, and an additional four suburban services receive partial MBTA funding.
As of 2024, the standard local bus fare is $1.70 for a one-way trip. The Silver Line routes serving the waterfront (SL1, SL2, SL3, SLW) apply the standard subway fare of $2.40. Express bus services charge a two-tier fare: a $1.70 local segment and a $4.25 express segment into downtown Boston.
Bus service experienced interruptions during the COVID-19 pandemic but was restored to pre-pandemic levels by 2021, although some routes remain suspended. Since 2018, the MBTA has been undertaking an extensive bus network redesign scheduled for completion by 2028, with initial modifications commencing in December 2024.
Silver Line
The Silver Line comprises six bus rapid transit routes promoted as rapid transit service. It consists of two main branches: the Waterfront lines (SL1, SL2, SL3, SLW shuttle), which run through the South Boston Transitway tunnel, and the Washington Street lines (SL4, SL5), which operate on surface streets. Waterfront routes require payment of subway fares, whereas Washington Street routes charge standard bus fares. All Silver Line vehicles are articulated buses measuring 60 feet in length; those on the Waterfront routes are hybrid models equipped with extended battery capabilities for electric operation within tunnels.
The SL5 route was introduced in 2002 as a replacement for the Washington Street Elevated rail line. The Shuttle service started in 2004, followed by the original SL2 and SL3 also in 2004, with SL1 launching in 2005 featuring dual-mode buses. The SL4 began operation in 2009 after plans for a Phase III tunnel were canceled. In 2018, a new SL3 route connecting Chelsea to South Station was inaugurated.
Crosstown
The two crosstown (CT) services provide limited-stop connections between major subway stations and key bus transfer points. Initially launched with three routes in 1994, CT1 was merged into route 1 in 2019.
Routes 1–121
These routes constitute the primary local transit network within the metropolitan area, many tracing their lineage back to original streetcar lines operated by the Boston Elevated Railway. Organized approximately clockwise from southeast to northeast sectors, these services have evolved through transitions from the Metropolitan Transit Authority to today's MBTA system while preserving much of their original framework despite some consolidations and expansions.
Seven routes—namely , , , , , , and —serve western suburban communities including Bedford, Waltham, Lexington, and Needham. These originated from the MBTA's 1972 acquisition of Middlesex and Boston Street Railway lines and were renumbered accordingly.
In 2004, fourteen routes such as , , , , , , , among others, were designated as key bus corridors due to their high ridership levels. These frequent services complement subway operations by facilitating access to Boston’s most densely populated neighborhoods. As part of a wider Bus Network Redesign initiative underway in 2024, the MBTA is phasing out the "key bus" designation while expanding frequent-route coverage. Notably, routes 28 and 39 utilize articulated buses measuring 60 feet to meet passenger demand.
Early morning service includes four round trips running between outlying stations and over multiple local routes primarily intended for station agents but open to all riders. These trips carry internal designations 191 through 194 but appear as route variants on schedules.
131–137
Routes numbered 131 through 137 operate within the Melrose vicinity, tracing their origins to former Eastern Massachusetts Street Railway lines that were incorporated into the MBTA system in 1968. Among these, routes 136 and 137, now discontinued, previously extended service to Lowell and Lawrence while under MBTA oversight. Additionally, route 132 was originally managed by Service Bus Lines before the MBTA assumed control in 1975.
171
Route 171 provides a limited early morning service, acting as a replacement for the former CT3 route that was curtailed from Logan Airport in 2002. Other routes in the 170 series historically catered to industrial zones but had relatively brief operational durations.
201–202
The 20 belt line was established by the M.T.A. in 1962, evolving from BERy’s original routes 20 and 21. In 2005, this line was divided into routes 201 and 202 to better indicate travel direction around the Fields Corner Loop.
210–245
Routes within the range of 210 to 245 primarily serve Quincy, originating from former Eastern Massachusetts Street Railway lines that were integrated into the MBTA network in 1968. Following the gradual inauguration of the Red Line’s Braintree Branch throughout the 1970s and 1980s, numerous routes were adjusted to end at rapid transit stations such as .
350–354
These services operate within the Burlington and Woburn regions, originally part of the Eastern Massachusetts Street Railway's Lowell–Boston corridor. The MBTA took over these lines in 1968, subsequently truncating the route to terminate at Burlington.
411–465
Covering Lynn and the North Shore, these routes include former Service Bus Lines (routes 411 and 430) acquired in 1975, alongside Eastern Massachusetts Street Railway lines absorbed in 1968. Weekend short-turn versions on Haymarket routes, indicated by a W suffix, conclude at Wonderland station.
501–558
These express services link Newton to downtown Boston utilizing the Massachusetts Turnpike (I-90). The MBTA introduced the 500 series in the 1960s to capitalize on the turnpike's new extension. The 550 series evolved from Middlesex and Boston Street Railway routes terminating at Newton Corner; these were extended downtown in the 1960s, absorbed by MBTA in 1972, and later scaled back to Newton Corner in 2020.
Privately operated routes
The MBTA provides partial funding for several suburban bus routes outside its primary service region that connect to MBTA transit lines. The radial commuter routes numbered 712 through 716 were originally run by private companies and later acquired—specifically, Rapid Transit Inc. operates routes 712 and 713, Nantasket Transportation manages route 714, and Hudson Bus Lines runs route 716.
Routes without numerical designations serve as local circulators developed by municipalities with MBTA financial support. Except for the Beverly Shuttle, which is managed by the Cape Ann Transportation Authority, all these services are operated under private contracts.
