Route 86 is a local bus route in Boston and Cambridge operated by the Massachusetts Bay Transportation Authority (MBTA) as part of MBTA bus service. It operates between Reservoir station and Harvard station, via Lower Allston and Brighton Center. In 2018, it had the 18th-highest weekday ridership on the system, though it ranked 37th by number of weekday trips. The last revenue service over those tracks ran in 1926, though it remains in use for non-revenue moves.
- The segment between Harvard Square and Union Square, Brighton, originated as horsecar lines of the Cambridge Railroad. The Western Avenue and Market Street segments opened as part of a line from Central Square, Cambridge in 1880, which was electrified in 1896.<!--Humphrey says April 14, 1894, but this is inconsistent with 1894/5 newspaper reports of horsecars on the line--> The North Harvard Street segment, which opened in 1883, was never electrified and was abandoned in the early 1890s. This diversion was eliminated by 1898, though the grade crossing was not replaced with a bridge until 1901.
Bus replacements
thumb|right|Streetcar tracks on Market Street in Brighton in 1930|alt=Streetcar tracks on an urban street
Horsecar and streetcar operations in Boston and surrounding municipalities were consolidated under the West End Street Railway in the 1880s; it was leased by the Boston Elevated Railway (BERy) in 1897. The BERy began operating bus service in 1922. On November 15, that shuttle was replaced with a new bus route at the city's request, with the intention of reducing congestion in Union Square. The Sullivan–Union tracks remained in use for non-revenue equipment moves until 1951.
On June 8, 1931, the Brighton Center–Central Square streetcar line was replaced with buses and extended south to Commonwealth Avenue. (The Western Avenue tracks would remain in use until 1950 for Watertown service, which is now bus route . The Commonwealth Avenue–Central Square route was designated route 63, Union Square–Union Square as route 86, and Central Square–Sullivan Square as route . The Western Avenue segment of route 63 was eliminated in February 1943 as a wartime measure, but it was extended slightly from Commonwealth Avenue to Cleveland Circle. The Western Avenue segment was resumed in 1946, forming a Cleveland Circle–Central Square route. In September 1962, the MTA through-routed several routes as part of experimental attempts to increase ridership. Route 63 was interlined with route to form a Cleveland Circle–Porter Square route, while route 91 was interlined with route to form a Central Square– route. Neither was successful; they returned to their previous terminals in March 1964 and June 1963, respectively.
thumb|left|A route 86 bus at Sullivan Square in 2006|alt=A transit bus in a station busway in an urban area
The MTA was in turn replaced by the Massachusetts Bay Transportation Authority (MBTA) in 1964. Sunday service on a Union Square, Somerville–Cleveland Circle route – a combination of routes 63, , and 86 – began in June 1973. In September 1977, peak hour route 86 service was extended to Sullivan Square, supplementing route 91. No short-term changes to the routing were recommended.
By 2022, scheduled headways were more consistent than during the 2018–19 review. In May 2022, the MBTA released a draft plan for a systemwide network redesign. The draft called for the 86 to be cut to a Harvard–Reservoir route; the Harvard–Sullivan Square segment would become an extension of route with higher frequency. A revised proposal in November 2022 kept these changes. The change occurred on December 15, 2024. Frequency was increased on the shortened 86 and the extended 109.