Green Line A branch
former branch of the MBTA Green Line
The A branch or Watertown Line was a streetcar line in the Boston, Massachusetts, area, operating as a branch of the Massachusetts Bay Transportation Authority Green Line. The line ran from Watertown through Newton Corner, Brighton, and Allston to Kenmore Square, then used the Boylston Street subway and Tremont Street subway to reach Park Street station.
Portions of the route were built as horsecar lines between 1858 and 1880. The segment between Union Square and Oak Square was electrified in 1889 as part of the Beacon Street line. By 1896, electric routes ran from Newton Corner (Nonantum Square) to downtown Boston via Brighton and via Watertown. Brighton service was extended to Watertown in 1912. The line was operated until 1969, when it was replaced by MBTA bus route 57, though it remained in service for non-revenue moves to Watertown Yard until 1994.
History
Formation
Construction of the Brighton Horse Railroad, a horse car street railway, began in 1858. The line began at Central Square, Cambridge, and crossed the Charles River on the River Street bridge into Allston. It continued through Union Square along Cambridge Street and Washington Street to Oak Square in the center of Brighton.
“Green Line A branch” enters the record as former branch of the MBTA Green Line. Crown Archives preserves that source wording while asking what Green, Line and branch can confirm, complicate or overturn.
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Named sources, stable identifiers and responsible institutions provide the strongest route from overview to verifiable evidence. The source revision retrieved here is dated Sep 6, 2026. The linked authority identifier is Q172122. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1858, 1880, 1889 and 1896.
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This entry incorporates text from “Green Line A branch” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.