43 (MBTA bus)

The 43 Ruggles Station - Park and Tremont Streets is a bus route in Boston, Massachusetts run by the Massachusetts Bay Transportation Authority (MBTA). The route runs southwest from downtown Boston along Tremont Street, ending at the Ruggles bus terminal and Orange Line transfer point. It is notable as the last streetcar service to use the since-covered-over Pleasant Street Incline before its bustitution; until the new Southwest Corridor relocation of the southern Orange Line opened in May 1987, the route continued down Tremont Street and Columbus Avenue to Egleston (on the old Washington Street Elevated).

Trackage along Tremont Street and Columbus Avenue was originally built in 1857 by the West Roxbury Railroad to provide service to Jamaica Plain (see Green Line "E" Branch for more about that line). It used Tremont Street and Columbus Avenue from downtown to Centre Street. Soon afterward, in 1859, a branch of this line was built west along Tremont Street to Brookline (this later became part of the 66).

The Tremont Street Subway opened to the four-track Pleasant Street Incline on October 1, 1897, and the western two tracks were connected to those running to the south along Tremont Street. However, between June 10, 1901 and November 29, 1908, the Main Line Elevated ran through the incline into the Tremont Street Subway, and Tremont Street streetcars again ran along the surface; this ended when the Elevated gained its own tunnel under Washington Street in 1908, and the Tremont Street Subway reverted to streetcar operation. At some time around then (after 1888), the tracks were extended the rest of the way to Egleston (and beyond, along Seaver Street).

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