By the mid-1860s horsecar lines reached to Lynn, Arlington, Watertown, Newton, West Roxbury, and Milton.
[2] In 1887 the various Boston-area horsecar companies (except for the Lynn and Boston Railroad) were all consolidated into the West End Street Railway.
In 1889 the West End Street Railway experimented with electric power for its streetcars; the results were so promising that it abandoned a cable car project already under construction.
Passengers could transfer for free between streetcars and rapid transit lines to complete their journeys to or from downtown.
[5]: 127 In 1904 the East Boston Tunnel opened and was initially used to allow streetcars from East Boston to reach downtown, but in 1924 it was converted into another rapid transit line (part of today's Blue Line) operated with free transfers to and from streetcars at Maverick station.
In the 1920s as competition from cars increased and bus technology improved, the BERy began replacing some of its streetcar lines with buses.
Bus conversions paused during World War II when gasoline and rubber were in limited supply, but resumed in the late 1940s.
It left Sullivan operated by a Boston Elevated Railway driver and ran via the tracks of BERy's 100 line.
At a stop called "Sheepfold" near Spot Pond in Middlesex Fells, the operator was replaced by an EMSR employee who drove the streetcar the rest of the way into Stoneham and alongside Main Street to the terminal at Farm Hill Station of the Boston and Maine Railroad Stoneham Branch.