Bay State Street Railway

The Eastern Massachusetts Street Railway (Eastern Mass) was a streetcar and later bus company in eastern Massachusetts, serving most suburbs of Boston, Massachusetts. It was acquired by Massachusetts Bay Transportation Authority, which still runs some of its routes, in 1968.

The Eastern Mass connected to the Boston Elevated Railway (BERy) system at many points; through service continued along BERy trackage at some.

Former Eastern Massachusetts Street Railway car 4387, built in 1918 by the Laconia Car Company, is preserved in operating condition at the Seashore Trolley Museum, in Kennebunkport, Maine.