Muso

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.