district in
Roxbury, Boston These routes provide almost all local service in the core of the metropolitan area; most were originally
Boston Elevated Railway streetcar routes. The modern system of route numbers first appeared on maps in 1936. Routes were numbered roughly clockwise from southeast (downtown and
South Boston) to northeast
East Boston. After several changes over the following five years, the numbering has stayed relatively consistent since 1941. The BERy folded into the
Metropolitan Transit Authority in 1947, and the M.T.A. in turn was reorganized as the MBTA in 1964. Despite some changes, including minor routes being merged into trunk routes, the core service network has remained roughly intact since the BERy eta. New routes have been added during the M.T.A. and MBTA eras. Seven routes – , , , , , , and – serve more distant western suburbs including
Bedford,
Waltham,
Lexington, and
Needham. They are descendants of routes acquired from the
Middlesex and Boston Street Railway in 1972, which were subsequently renumbered using previously discontinued designations. As part of the implementation of the MBTA's Bus Network Redesign program beginning in 2024, the key bus route terminology is being phased out and replaced by a larger frequent route network. Routes 28 and 39 use 60-foot articulated buses. Four early morning round trips are run between outlying stations and , each running over portions of several local routes. Although intended primarily for station agents, they are open to all passengers. The trips are internally numbered 191–194, but are shown in timetables as variants of local routes. }
61 ==131–137==