September 1 is the anniversary of the opening of the Tremont Street Subway!
People like to say the entire MBTA system is the oldest in the United States. But if you research more into it, this statement really only applies to the Tremont Street Subway and other central segments including the Boylston Street Subway, the Washington Street Tunnel, and the Cambridge Tunnel. Some of the outer portions of lines (such as the Haymarket North Extension, the Southwest Corridor, the South Shore Extension, and the Northwest Extension) opened in the 1970's and 1980's, which was not too long ago.
The Tremont Street Subway opened to the public on September 1, 1897. And the first two stations to accompany the subway, Boylston Street and Park Street, opened two days later. Before the building of this subway tunnel underneath Tremont Street, streetcars ran on the congested streets of downtown. Initial portals for trolleys to enter and exit the subway were the Public Garden Incline (located at the intersection of Boylston Street and Charles Street) and the Pleasant Street Incline (located at present Eliot Norton Park).
The subway eventually expanded underneath Boylston Street (Boylston Street Subway) further west to Copley Square (formerly Art Square), with a new portal at Kenmore Square (formerly Governor's Square). This portal was closed when the subway expanded a little bit more to create new portals at Blandford Street on the Commonwealth Avenue (B) Line, Saint Mary's Street on the Beacon Street (C) Line. And do not forget the Northeastern Incline on the Arborway (E) Line, as well as the Fenway Incline on the Highland Branch (D).
The portion of the Tremont Street Subway that is still in use today is between Boylston Street and Park Street. The stretch of the Tremont Street Subway south of Boylston Street down to the site of the Pleasant Street Incline is no longer in use and is considered abandoned. This tunnel was originally used by streetcars that went to City Point via Broadway, as well as trolleys that went down to Egleston Square or Lenox Street via Tremont Street. Both of these former streetcar lines are now done by bus route 9, which goes to Copley Square instead of into the subway, and bus route 43 to Ruggles Street.
After 118 years, the Tremont Street Subway still remains the most important section of the Green Line, bringing people to and from downtown each day.