73 (MBTA bus)

Massachusetts Bay Transportation Authority Primary Bus Routes

Company type	Public transit service
Industry	Public transportation
Founded	2004
Headquarters	Boston , United States
Area served	Boston metropolitan area
Products	Bus transit services
Website	www.mbta.com

Primary bus routes within the Massachusetts Bay Transportation Authority (MBTA) network were defined as the 15 routes exhibiting the highest ridership and meeting frequency benchmarks according to the 2004 MBTA Service Policy. Collectively, these routes represented roughly 40% of the system’s total bus passenger volume. They delivered frequent transit service throughout Boston’s most densely populated neighborhoods and linked seamlessly with other MBTA modes, facilitating extensive regional connectivity.

Designated as integral elements of the MBTA’s core network, these primary bus routes appeared on updated transit maps displayed at subway stations and public venues. These schematic representations illustrated rapid transit lines, bus rapid transit corridors, commuter rail, and the primary bus routes. This classification directed targeted service enhancements such as late-night service trials and served as a focal point for urban development planning and transit engineering research. With the implementation of the 2024 Bus Network Redesign, the terminology "key bus route" is being superseded by a more inclusive high-frequency route network concept.

History

The MBTA initiated a program in November 2006 aimed at elevating service quality on its primary bus routes. The 2008 Service Plan recommended improvements for several lines, including upgrading Route 31 to meet primary route criteria. Subsequently, a $10 million Key Routes Improvement Project was launched, funded in part by the American Recovery and Reinvestment Act of 2009. Although Silver Line services were initially encompassed within this project, they were later managed separately. The initiative concluded in 2013, with some proposed upgrades remaining incomplete. Performance metrics indicated that service reliability on these primary routes was superior to other lines—achieving 75% adherence to scheduled frequencies compared to 61% in June 2017.

An analysis conducted in 2012 revealed that areas near primary bus routes experienced reduced taxicab trip generation, suggesting that these high-frequency corridors effectively competed with taxi services for passengers.

In April 2014, a one-year pilot program introduced extended late-night service on both primary bus and rapid transit lines, dependent on ridership levels and sponsorship support. By April 2015, operating hours were curtailed, resulting in the elimination of late-night service on five of the fifteen primary routes; complete discontinuation followed in March 2016.

Primary bus routes were highlighted in Boston Mayor Marty Walsh’s "Go Boston 2030" plan, which sought to ensure every household was within a ten-minute walk of either a T station or a primary route stop. The plan proposed a new primary route linking Longwood Medical Area with JFK/UMass through Roxbury.

In May 2022, the MBTA unveiled a draft Bus Network Redesign proposal suggesting modifications to most primary routes while elevating others to form an expanded high-frequency network complementing rapid transit services. A revised version was released in November 2022.

Criteria for Primary Routes

The MBTA’s Service Delivery Policy defines Primary Bus Routes according to five key factors:

• Elevated ridership demand
• Integration within the transit system
• Extensive geographic reach
• Support for significant new developments
• Functioning as bus rapid transit

Service Standards

Primary routes are held to stricter service span and frequency requirements than typical local routes. The tables below outline these standards.

Route Category	Minimum Service Span
Local	Weekdays	7:00 AM – 6:30 PM
	Saturdays	8:00 AM – 6:30 PM
	Sundays	10:00 AM – 6:30 PM
Primary	Weekdays	6:00 AM – Midnight
	Saturdays	6:00 AM – Midnight
	Sundays	7:00 AM – Midnight

Route Category	Minimum Service Frequency
Local	Morning & Evening Peak	Every 30 minutes
	Off-Peak Hours	Every 60 minutes
	Weekends	Every 60 minutes
Primary	Morning & Evening Peak	Every 10 minutes
	Midday Periods	Every 15 minutes
	Evenings & Weekends	Every 20 minutes

Route list

The MBTA identified 15 principal routes: 1, 15, 22, 23, 28, 32, 39, 57, 66, 71, 73, 77, 111, 116, and 117. These corridors have been prioritized for enhancements such as limited-stop or express services in response to feedback from both officials and the community.

1

The 1 Harvard Square–Nubian Station line connects Cambridge with Roxbury. It was established in September 1962 by combining two separate routes that previously terminated at Massachusetts Avenue—the 76 Harvard–Massachusetts station and the 47 Massachusetts station–Dudley. In May 1987, its alignment shifted from Washington Street southeastward onto Albany Street and Melnea Cass Boulevard to provide service to Boston Medical Center. The route mainly travels along Massachusetts Avenue, linking Harvard past the Massachusetts Institute of Technology, crossing the Charles River via the Harvard Bridge into Boston. It continues beyond the Berklee College of Music to Boston Medical Center before heading southwest to Nubian station using Albany Street and Melnea Cass Boulevard.

By 2015, Cambridge intended to introduce signal priority for route 1 at selected intersections to enhance operational efficiency. The network proposals of 2022 did not include any modifications for this route.

In October 2023, transit advocacy organization Transitmatters identified the 1 bus as the slowest and most congested MBTA route, recording an average velocity of 6.55 mph and a bunching frequency of 17.7%, highlighting notable reliability issues.

15

The 15 Fields Corner Station or St. Peter's Square–Ruggles Station route begins at St. Peter's Square in northern Dorchester, proceeding north on Bowdoin Street, west along Hancock Street, then north on Columbia Street toward Uphams Corner. From there it heads west on Dudley Street to Nubian station, continues westward on Malcolm X Boulevard, and finally turns north on Tremont Street to reach Ruggles station. Evening and weekend services terminate at Fields Corner station, traveling via Geneva Avenue and Bowdoin Street back to St. Peter's Square.

On April 6, 1962, buses replaced the former trackless trolleys operating on the 15 Kane Square–Dudley via Uphams Corner route. Following the Orange Line’s relocation to the Southwest Corridor in May 1987, this route was extended to Ruggles. Service at Kane Square was slightly lengthened to St. Peter's Square on August 25, 2024.

The draft network plan from May 2022 suggested extending this route westward to Oak Square, absorbing route , thereby creating an Oak Square–Fields Corner corridor. However, by November 2022, plans reverted to terminating the route at Ruggles while maintaining route 65 as a separate line.

22

The 22 Ashmont Station–Ruggles Station via Talbot Ave operates from Ashmont northwest toward the former location of Egleston station, then continues north along Columbus Avenue and Tremont Street, running parallel to the Orange Line before concluding at Ruggles.

This route replaced the previous trackless trolley service on April 6, 1962, originally running as the 22 Ashmont–Dudley via Talbot and Warren. Unlike its current path, it once proceeded north along Warren Street to , before being extended to Ruggles in May 1987 after the Orange Line was relocated. Both the May and November 2022 network proposals recommended shifting its inner terminus to the Longwood Medical Area.

23

The 23 Ashmont Station–Ruggles Station via Washington Street operates between the same termini as route 22 but follows an alternative course. Beginning at Ashmont on Talbot Avenue, it heads north along Washington Street, then proceeds via Warren Street to Nubian station. From Nubian, the route continues westward along Malcolm X Boulevard to Roxbury Crossing, before heading north on Tremont Street to reach Ruggles station.

On April 7, 1962, buses succeeded the former trackless trolley service, running initially as route 22 Ashmont–Dudley via Washington Street and Warren. This service was extended to Ruggles in May 1987 coinciding with the Orange Line relocation. A 2017 analysis highlighted overcrowding concerns on routes 23 and 28, recommending enhancements and extensions of route 29 to address these issues. Additionally, a city-sponsored fare-free initiative covers routes 23, 28, and 29 from March 1, 2022, through February 28, 2026. No modifications for route 23 were included in either the May or November 2022 network proposals.

28

The 28 Mattapan Station–Ruggles Station line connects the Grove Hall and Mattapan neighborhoods via Blue Hill Avenue, a principal arterial corridor. Historically, Blue Hill Avenue accommodated streetcars operating on exclusive rights-of-way until their replacement by bus service in 1955. Established in 1987 to complement route 29, route 28 became the main transit option along Blue Hill Avenue by 1989, with passenger shelters installed in 2001. Between 2006 and 2010, a morning peak short-turn variant operated under route number 25.

The 2003 Program for Mass Transportation evaluated multiple Silver Line expansion options, including a bus rapid transit (BRT) overlay for route 28. In 2009, a state proposal introduced the 28X, a limited-stop BRT line designed for this heavily trafficked New England corridor. The plan included dedicated bus lanes and queue jump lanes, with an estimated budget of $114 million and construction aimed to begin in 2010 for a projected opening in 2012.

Community opposition arose due to inadequate local engagement, concerns over parking removal, median modifications, and extended construction impacts. Consequently, the state withdrew the project late in 2009. In June 2010, the MBTA deployed articulated 60-foot buses on route 28 to boost capacity despite resident objections related to stop eliminations in Grove Hall. The 2012 Roxbury–Dorchester–Mattapan Transit Needs Study suggested implementing the express-style 28X service without constructing new infrastructure.

In August 2020, MBTA and Boston applied for $15 million in federal funds toward a $30 million Blue Hill Avenue improvement project featuring center-running bus lanes targeted for completion by year-end 2021; however, this request was denied in September. A subsequent $25 million federal funding application was submitted in July 2021. From August 2021 through February 2022, a city-funded pilot provided fare-free rides and all-door boarding on route 28 to improve punctuality on this frequently delayed line. Following this pilot, fare-free service was extended on routes 23, 28, and 29 through February 2026. In November 2021, Boston secured a $15 million federal grant supporting a $39.5 million Blue Hill Avenue reconstruction project.

The transit network plans released in May and November of 2022 proposed extending route 28 beyond Roxbury Crossing toward , routing through the Longwood Medical Area while discontinuing its segment between Roxbury Crossing and Ruggles. In February 2024, the city announced a $44 million Blue Hill Avenue reconstruction including center-running bus lanes with construction anticipated to commence in 2026.

32

The 32 Wolcott or Cleary Square–Forest Hills Station line runs along Hyde Park Avenue, connecting Forest Hills to Readville while serving the neighborhoods of Jamaica Plain, Roslindale, and Hyde Park. Its entire path closely follows the commuter rail tracks.

Originally a trolley route from Forest Hills to Cleary Square until 1953, Route 32 transitioned to trackless trolley operation thereafter. By 1958, diesel buses replaced trackless trolleys on the segment south of Forest Hills. A turnaround loop for the trackless trolley was situated at the intersection of Hyde Park Avenue and Pine Street.

In 1981, the previous Route 31, which ran between Mattapan Square and Wolcott Square, was combined with Route 32 at Cleary Square, resulting in the current Route 32 Forest Hills–Wolcott Square. Meanwhile, Route 50, which served both Cleary Square and Forest Hills via Roslindale, was rerouted to cover the Summer Street Elderly Housing area. The network plans released in May and November 2022 did not propose any modifications to Route 32.

39

The 39 Forest Hills Station–Back Bay Station route was established in December 1985 as a replacement for the Green Line E branch service between Heath Street and Arborway. It parallels the Green Line from Heath Street to Copley and offers connections to the Orange Line and commuter rail at both ends, including Amtrak access at Back Bay.

Route 39 was notable for being the first MBTA route to deploy articulated buses regularly, beginning in late 2005; this innovation was later adopted by other routes such as the 28. By 2013, it ranked as Boston’s second busiest bus line. Its substantial ridership contributed to the expansion project at Forest Hills station during the Casey Arborway reconstruction.

The draft network plan from May 2022 suggested extending Route 39 through via and , replacing segments of routes , , and , while eliminating service between Longwood Avenue and Back Bay. However, the November 2022 draft plan restored Route 39 to its previous alignment and instead proposed a more frequent Route 47 extension to Union Square.

57

The 57 Watertown Yard–Kenmore Station route operates through Boston, Newton, and Watertown areas. It serves as a successor to the Green Line A branch service that ended in 1969. Previously, Route 57 offered limited-stop service within Boston city limits—specifically no passenger pickups along Commonwealth Avenue between Packard's Corner and Kenmore—a practice that ceased in December 2006. The May and November 2022 network plans did not include any alterations for this route.

66

The 66 Harvard Square–Nubian Station via Allston route has its origins as a trolley line, commencing at Nubian Square in Roxbury and crossing the Southwest Corridor Park near Roxbury Crossing. It shares portions of its path with Route 39 and briefly follows the Green Line E branch from Brigham Circle up to Boston’s city limits. Traveling along Harvard Street, this route serves Brookline and Allston neighborhoods, detouring through Union Square (Allston) before proceeding via Cambridge Street and North Harvard Street to conclude at Harvard Square in Cambridge. The line links several transit services including the Silver Line, Orange Line, multiple Green Line branches (B, C, D, E), and the Red Line. No changes were proposed for this route in either the May or November 2022 network plans. In August 2024, northbound trips were rerouted through the Harvard Bus Tunnel.

71

The 71 Watertown Square–Harvard station route originates at the lower level of the Harvard bus tunnel, then heads south onto Mount Auburn Street before continuing westward into Watertown, ending at Watertown Square.

At Harvard, buses complete a turnaround by exiting the tunnel and navigating a loop via Massachusetts Avenue, Garden Street, and Waterhouse Street prior to re-entering the tunnel. On the Watertown side, a dedicated loop on private right-of-way facilitates vehicle turning and passenger boarding.

Streetcar operations on this line ceased on September 4, 1958, subsequently replaced by trackless trolleys until March 13, 2022. In 2017, routes 71 and 73 were chosen to participate in a bus rapid transit pilot initiative.

Routes 71 and 73, along with neighboring lines , and , continued trolleybus ("trackless trolley") service well beyond the discontinuation of other MBTA trolleybus routes, representing some of the final trolleybus operations in Boston. These routes transitioned to diesel buses in March 2022. While no modifications were suggested in the 2022 network proposals, Watertown intends a slight extension to Watertown Yard as part of an overall redesign of Watertown Square.

73

The 73 Waverley Square–Harvard Station route also begins within the Harvard bus tunnel, sharing its path with route 71 along Mount Auburn Street through Cambridge and Watertown. It then diverges onto Belmont Street—which forms the boundary between Belmont and Watertown—before proceeding along Trapelo Road in Belmont to terminate at Waverley Square. The route loops near the Waverley commuter rail station on the Fitchburg Line.

Initially served by streetcars until the 1950s, this corridor saw short-turn trackless trolley service commence in 1957 between Harvard and Benton Square. The entire line transitioned from streetcars to trackless trolleys in 1958 and maintained this mode until March 13, 2022. No alterations for route 73 appeared in either the May or November 2022 network plans.

77

The 77 Arlington Heights–Harvard Station line links Arlington with Harvard station via Massachusetts Avenue. Prior to the opening of the Red Line Northwest Extension in the 1980s, routes 77 and 77A served as the main transit options northwest of Harvard, with combined streetcar frequencies under one minute during peak periods in 1945. Route 77 converted to diesel buses in 1955; meanwhile, route 77A—providing short-turn service to the North Cambridge carhouse—switched to trolleybus operation in 1958 to free up streetcars for the conversion of the Highland branch and to eliminate boarding islands that hindered automobile traffic flow. Historically, route 77A handled all local stops south of the carhouse while route 77 operated limited-stop service; from 1998 through 2005, route 77 increasingly replaced route 77A operations until route 77A was fully discontinued in 2022. In 2017, Arlington pursued a private grant aimed at implementing transit signal priority, queue jump lanes, and potential bus-only lanes along its section of the route. No changes to this route were proposed in either the May or November 2022 network plans.

111

The 111 Woodlawn–Haymarket Station line connects downtown Boston with sections of Chelsea, traversing the Bill Russell Bridge and Tobin Bridge. Initially operated as streetcars by the Boston Elevated Railway between Chelsea Square and Woodlawn starting in 1936, the service transitioned to buses in October of the same year. In April 1975, following the closure of the Charlestown Elevated, the route was extended to Haymarket. Additional partial extensions beyond Woodlawn were introduced in January 2001. However, service beyond Woodlawn was discontinued in September 2019, and in December 2021, trips that previously short-turned at Cary Square were replaced by those terminating at Woodlawn.

Among the MBTA’s numbered bus routes, the 111 is one of the most frequent, offering buses every five minutes during peak periods. The route remained unchanged in both the May and November 2022 network proposals.

116/117

The 116 Wonderland Station–Maverick Station via Revere Street and 117 Wonderland Station–Maverick Station via Beach Street routes provided service through East Boston, Chelsea, and Revere. These two lines shared most of their corridors within East Boston and Revere, differing only near Wonderland. According to the network plans released in May and November 2022, route 117 was slated for discontinuation, with its segment between Broadway and Wonderland station incorporated into an extended version of route , maintaining key bus route frequencies. This adjustment was implemented on December 15, 2024.

See also

• List of MBTA bus routes
• MBTA crosstown bus routes
• MBTA Silver Line (previously included in key routes)
• Free public transport in Boston

External links

• MBTA – routes , , , , , , , , , , , , , ,
• MBTA - Key Bus Route Improvement Program