504 (MBTA bus)
| Company type | Streetcar route |
|---|---|
| Industry | Public transport |
| Founded | 1858 |
| Defunct | 1969 |
| Fate | Replaced by MBTA bus route 57 |
Area served | Boston metropolitan area |
| Products | Streetcar transit service |
| Parent | Massachusetts Bay Transportation Authority (MBTA) |
The A branch, also known as the Watertown Line, was a streetcar route within the Boston metropolitan area, functioning as an extension of the Massachusetts Bay Transportation Authority (MBTA) Green Line. This line connected Watertown with Kenmore Square, passing through Newton Corner, Brighton, and Allston, before continuing via the Boylston Street and Tremont Street subways to Park Street station.
Segments of this route originated as horse-drawn streetcar lines constructed between 1858 and 1880. The portion running between Union Square and Oak Square was electrified in 1889, becoming part of the Beacon Street line. By 1896, electric streetcar services linked Newton Corner (Nonantum Square) to downtown Boston through Brighton and Watertown. Service to Brighton was extended to Watertown in 1912. The streetcar operated until 1969, when it was discontinued and replaced by MBTA bus route 57; however, the tracks remained in use for non-revenue movements to Watertown Yard until 1994.
Origins
The Brighton Horse Railroad, a horsecar street railway system, began construction in 1858. Its route originated at Central Square in Cambridge, crossed the Charles River into Allston, and proceeded through Union Square to Oak Square in Brighton. This line was managed by the Union Street Railway, which served as a holding company for the Cambridge Railroad network. After resolving conflicts related to track crossings, service officially commenced on November 15, 1858. By April 1878, service frequency improved to a car every thirty minutes. In 1880, an additional Brighton–Cambridge route opened via Market Street and Western Avenue. Although a planned expansion from Oak Square to Nonantum Square was not realized at that time, a separate line connected Watertown with Nonantum Square.
During the late 1880s, the West End Street Railway consolidated several local horsecar lines including the Cambridge Railroad. It inaugurated its first electric streetcar route on January 3, 1889, running between the Allston Carhouse and Park Square via Harvard Street, Beacon Street, Massachusetts Avenue, and Boylston Street. Shortly thereafter, electric service extended to Oak Square. Electric operations between Watertown and Mount Auburn commenced in December 1893; double-tracking followed later that decade. The Western Avenue line was electrified and double-tracked by August 1896. This line was the final one crossing the West Boston Bridge to be converted from horse-drawn cars; previously passengers transferred at Central Square onto electric cars bound for Boston.
On May 18, 1896, new tracks were laid from Union Square eastward along North Beacon Street and Commonwealth Avenue reaching Kenmore Square where they connected with existing Beacon Street tracks. By June 13 of that year, the western terminus had been extended near Newton Corner (Nonantum Square). Service from Newton via Commonwealth Avenue began utilizing the Tremont Street subway in November 1897. A route linking Nonantum Square to City Point through Allston and Coolidge Corner started operations in August 1900. In December 1912, service expanded northward to Watertown using existing tracks along Galen Street. The line also accommodated freight transport during the early twentieth century.
The Boylston Street subway opened up to Kenmore Square on October 3, 1914; Watertown-bound streetcars via Brighton Center were immediately rerouted through this tunnel. Mid-1915 saw the introduction of high-capacity center-entrance streetcars as trailers on this corridor. Evening peak short-turn trips originating from Oak Square were extended to Watertown by February 1922. The Blandford Street portal on Commonwealth Avenue west of Kenmore became operational in October 1932, representing the last significant modification to the route. In 1941, this line became Boston’s pioneer for primary service using new PCC streetcars, replacing older Types 4 and 5 models.
North Beacon Street line
In June 1894, the West End sought municipal approval to construct a transit line along North Beacon Street, spanning from Union Square to the Watertown boundary. Shortly thereafter, the Newtonville and Watertown Street Railway obtained authorization to build the segment between and Union Square, planning to utilize West End tracks for access to downtown Boston. Despite opposition from the West End, the Watertown Arsenal granted permission in 1896, leading to the line's construction in 1898.
After operational conflicts arose between its parent company, the Newton and Boston Street Railway, and the BERy, service commenced in 1900. On November 18 of that year, through service connecting Watertown with the Tremont Street subway began as a branch of the Newton-Brighton line. The BERy purchased this line from Newton and Boston in 1907. Uncommonly for BERy routes, the section west of Market Street remained single-tracked.
The Newton Street Railway, later known as the Middlesex and Boston Street Railway, initiated Waltham–Park Street service via North Beacon Street on February 23, 1903. This route was redirected to Central Square in 1912, moving away from North Beacon Street. Meanwhile, Oak Square–Boston service was progressively shortened, but Watertown–Park Street service along North Beacon persisted. Following the Boylston Street subway's opening in October 1914, North Beacon Street service was reduced first to a shuttle between Watertown and Union Square, then further scaled back to a Brighton/Watertown shuttle on June 2, 1917.
On February 23, 1922, bus service replaced the North Beacon Street shuttle. A short-lived bus route connecting Watertown and Arsenal Street bridge operated during 1925–26. Concurrently, in December 1925, the Central Square–Union Square line was rerouted via Western Avenue and Soldiers Field Road; by September 1926, a new bus route on River Street extended to Union Square, supplanting streetcar service. These two bus lines merged in February 1933 to eliminate transfers; this combined route continues today as the route 64 bus.
Closure
Prior to 1967, the Watertown Line was designated as route 69; meanwhile, route number 57 was originally assigned to short-turn trips on Huntington Avenue. The line carried the letter "A" as it represented the northernmost branch of the Green Line, featuring turnback loops at Union Square, Oak Square, and its Watertown terminus. From 1915 until 1962, Braves Field had a special loop serving events on the Commonwealth Avenue line.
The Riverside Line's inauguration in 1959 prompted Cambridge streetcar routes to convert to trackless trolley operation, freeing PCC streetcars for Riverside service. However, by the late 1960s, aging PCC fleets combined with maintenance challenges resulted in a shortage of Green Line streetcars. Consequently, the MBTA declared a "trial" suspension of the A branch.
Given its extensive street-running segments and previous resistance toward extending service beyond Newton Corner, this branch was selected for closure. Streetcar operations ceased on June 20, 1969; bus service under route 57 commenced the following day.
Track removal
Following 1969, tracks remained primarily to allow access to Watertown Carhouse for vehicle maintenance. The final use occurred in 1993 when PCC streetcars destined for the Mattapan Line underwent refurbishment there. Overhead wiring was dismantled in March 1994.
By summer 1996—coinciding with resurfacing work on North Beacon Street—the majority of tracks and related infrastructure were removed. Some remnants still exist within Watertown Yard and as a short track stub at Packard's Corner that once stored disabled trains; this stub was shortened during the mid-2000s with its switch disconnected in 2014 and eventually paved over by 2020.
Proposals to restore direct downtown rail service from this northern corridor without requiring transfers at Kenmore were considered but ultimately rejected due to high costs and safety concerns compared with existing bus alternatives.
Route 57
The 57 Watertown Yard–Kenmore station bus service was introduced in 1969, taking over from the A branch streetcar line. Its path remains largely consistent with the former streetcar route, except at the Newton Corner rotary, where buses follow regular traffic patterns instead of a dedicated counterflow lane. Initially, the 57 operated as a limited-stop service between Packards Corner and Kenmore to complement the "B" branch’s local stops; however, in December 2006, it transitioned to making all local stops along Commonwealth Avenue.
Before 2007, passengers boarding at Watertown were required to pay double fares due to the elimination of free transfers. This changed on January 1, 2007, when a new fare policy introduced free transfers for CharlieCard users.
Additional short-turn trips during peak hours between Oak Square and Kenmore were discontinued in 1971 but reinstated for morning service in 1987. Between 1999 and 2013, trips running from Brighton Center to Kenmore supplemented these services. On September 1, 2008, the MBTA launched the 57A Oak Square–Kenmore short-turn route during weekday rush periods to alleviate crowding; roughly half of the peak trips operated as 57A. In December 2020, Oak Square short-turns were mostly eliminated except for a few school-day runs, while overall frequency on the full route increased.
Route 57 remains one of the MBTA’s principal bus lines, maintaining headways of 10 to 12 minutes throughout operating hours. As of 2012, routes 57 and 57A combined ranked ninth in systemwide ridership with over 10,000 weekday boardings. During weekday peak and midday periods, buses are dispatched from Albany Street Bus Facility; evening, weekend, and holiday operations are handled out of Cabot Garage. An early morning trip extending to Haymarket—designated internally as route 191—was established in 1960 primarily for MBTA staff but is publicly listed as part of route 57.
A review conducted by the MBTA in 2018–19 highlighted issues of overcrowding and inconsistent service on route 57 but did not suggest immediate alterations. The comprehensive bus network redesign proposed in 2022 recommended increasing frequency to at least every fifteen minutes throughout all hours of operation. The short-turn 57A service was briefly reinstated in December 2024 but was discontinued again by April 2025.
Express buses
Two express routes run west of Brighton Center towards downtown Boston via Copley Square:
- 501 Brighton Center–Federal Street & Franklin Street
- 504 Watertown Yard–Federal Street & Franklin Street
Express bus service from Brighton and Watertown dates back to when the "A" branch was still active. The initial route, numbered 61 Watertown/Newton Corner–Downtown, began operations in July 1967 and underwent renumbering and routing adjustments throughout the late 1960s. By June 1970, express routes adopted numbers in the 300-series to denote their express nature, with further modifications continuing through the following two decades.
Service expansions during midday and Saturdays took place in the early 1980s. A stop at Copley Square was added in December 1989 under route number 304. In September 1996, these routes were renumbered as they are known today: routes 501, 502, and 504. Route 503 was later introduced in January 2005. Routing changes for inbound afternoon trips via Cambridge Street occurred in both 2014 and again in 2019.
An MBTA review from 2018–19 identified challenges with stop spacing and schedule reliability on routes 501 and 503; however, routes 502 and 504 did not exhibit significant issues. To enhance operational efficiency, the MBTA recommended implementing direct outbound routing for routes 502 and 504—a modification that took effect in September 2019—while routes 501 and 503 adjusted their Newton Corner stops accordingly.
The COVID-19 pandemic led to service reductions beginning March 2020: routes 502 and 503 were suspended entirely; meanwhile, routes 501 and 504 operated on reduced schedules. Route 504 assumed much of route 502’s former service pattern by running via Copley on most trips and resumed its outbound loop through Newton Corner. Route 501 was suspended from June through August of that year; upon resuming service, it began including stops at Copley Square.
Proposals issued in May 2022 sought to make these pandemic-related changes permanent by limiting routes 501 and 504 to weekday peak periods only. A November update that year restored midday service on route 504.