thumb|right|Ex-Eastern Mass. Street Railway car 4387 at the [[Seashore Trolley Museum]]
thumb|right|1930s map of Eastern Mass streetcar and bus lines
The Eastern Massachusetts Street Railway (Eastern Mass) was a streetcar and later bus company in eastern Massachusetts, serving northern and southern suburbs of Boston, Massachusetts. Its precursor company was the Bay State Street Railway, which it absorbed in 1919. It was acquired by Massachusetts Bay Transportation Authority, which still runs some of its routes, in 1968.
History
The Lynn and Boston Street Railway originally ran into downtown Boston via the Chelsea Bridge and Warren Bridge, running over tracks of the Boston Elevated Railway (BERy) and its precursors in Charlestown and Boston.
The year-long closure of the Chelsea Bridge for repairs in 1935 eliminated the route to the subway (though early plans called for streetcar service to continue during repairs.) On January 14, 1935, the Eastern Mass curtailed all routes to Chelsea Square as the bridge closed. Buses operated between Chelsea Square and Haymarket Square via the Meridian Street Bridge and the newly opened Sumner Tunnel under a permit issued just two days prior. The bridge reopened on December 23, 1935, without streetcar tracks; the Eastern Mass continued its bus operations.
On August 10, 1935, the Eastern Mass began operation of a Middleton–Salem–Lynn–Boston bus route. The new route used the American Legion Highway, Lee Burbank Highway, and William McClellan Highway through Revere to reach the Sumner Tunnel, rather than the streetcar route on Broadway and Meridian Street. The transfer took effect on June 10, 1936, at a cost to the BERy of $1.5 million. Chelsea–Lynn service was jointly operated by the two companies for a short period, but soon discontinued in favor of a transfer between the Boston–Lynn bus route and BERy streetcar service on Revere Street. Several of the lines were converted to trackless trolley by the BERy in 1937, while three remained as streetcar lines until the Revere Extension opened in 1952.
Major cities served
The Eastern Massachusetts Street Railway, and previously the Bay State Street Railway, ran direct or indirect interurban services from Boston to these cities.