In May 2020, the E branch was cut back to North Station for construction of the Green Line Extension, as part of which it was temporarily extended to Union Square in March 2022.

[29] In 1894–96, the city paved Huntington Avenue as a boulevard, with the streetcar tracks moved into a dedicated median east of Brigham Circle.

It initially terminated at Chestnut Hill, but was extended over BERy tracks on Boylston Street and Huntington Avenue to Park Square on July 6.

[49] Requests from local residents and politicians to extend the South Huntington Avenue line from Jamaica Plain Carhouse to Forest Hills began before the extension was completed and continued throughout the 1910s.

[67] By 1921, four subway services operated on Huntington Avenue: Lake Street, Jamaica Plain, Longwood, and Opera Place short turns.

[49] The Allston–Dudley route was replaced by buses on September 10, 1938, with the Brookline Village cars from Huntington Avenue cut back as additional Brigham Circle short turns.

[75][76]: 111 A subway for the Huntington Avenue line was proposed as early as 1906 to remove streetcars from congested Boylston Street and Copley Square.

[78][79] In May 1924, the state legislature directed the Metropolitan District Commission to plan an expanded rapid transit system in Boston, including an extension of the Boylston street Subway under Governors Square.

[80] The report, released in December 1926, called for the existing streetcar tunnels in Boston to be reorganized into two rapid transit lines with high-floor rolling stock.

Streetcar lines on Tremont Street and Huntington Avenue would connect with rapid transit trains at a surface-level transfer station at Brigham Circle.

The BERy did not approve the project because the portion east of Copley Square would have duplicated the existing subways at considerable cost, and it would not relieve congestion at the intersection with Massachusetts Avenue; the state act did not allow for any modifications to the route.

[82][83][84] Mayor James Michael Curley advanced a new plan in 1933, calling for an $8.5 million subway from Copley Square to Longwood Avenue, to be funded by the National Industrial Recovery Act rather than imposing local debt.

[87] In October 1936, construction of the subway to just shy of West Newton Street was approved as a federal Works Progress Administration (WPA) project.

[102] From September 11, 1976, to January 1, 1977, service was replaced with buses at night to allow installation of new lighting and electrical equipment in the Huntington Avenue subway.

[49] On January 1, all peak and midday service was cut to Heath Street as winter weather caused a car shortage; buses designated route 39 ran between Arborway and Copley.

[49] Continued streetcar shortages and delays with the new Boeing LRVs caused weekday service to be replaced with buses past Heath Street on October 17, 1977.

[49] From October 12 to November 11, 1983, the line was cut back to Brigham Circle (with double-ended LRVs) due to Southwest Corridor construction near Arborway, with route 39 buses running.

[49] LRV service was resumed to Brigham Circle on July 26, 1986; the downtown terminal was Lechmere on weekdays, and Government Center nights and weekends.

[49] That December, route 39 was extended to Back Bay station to connect with the Orange Line; fares were reduced from subway to bus prices.

[49] Whether to restore E branch service to Arborway became controversial; much of Jamaica Plain wanted the line to return, while the MBTA did not wish to resume using the long street-running section.

[111] To settle a lawsuit with the Conservation Law Foundation, the Massachusetts Executive Office of Transportation and Construction (EOTC) agreed to environmental mitigation for increased automobile emissions due to the Central Artery/Tunnel Project.

In 2000, an Administrative Consent Order (ACO) affirmed specific project commitments, including restoration of streetcar service beyond Heath Street to Arborway.

[112][113] After some MBTA and community opposition, a revised settlement resulted in the substitution of other projects with similar regional air quality benefits, though no longer localized along the E branch corridor.

[114] A 2004 study stated that since tracks to Arborway would be street-running along South and Centre streets, trolley traffic would increase local congestion and could potentially block emergency vehicles.

[115] The Arborway Committee filed suit in 2007, but an appeals court ruled in January 2011 that the lawsuit was a decade too late to be considered – effectively ending any attempt for the restoration of streetcar service for the foreseeable future.

[49] From July 24 to December 17, 2000, the line was cut back to Brigham Circle for track work on South Huntington Avenue, with route 39 supplemented by express service.

[49] The accessible platforms at Northeastern, Museum of Fine Arts, Longwood, Brigham Circle, and Heath Street - part of a $32 million modification of thirteen B, C, and E branch stations - were completed in 2003.

[131] On October 13, 2012, the cut was quietly reversed by reducing frequency on the branch slightly, thus allowing the same equipment to cover the full line at no additional cost.

[142][143] The section between Union Square and Government Center was closed from August 22 to September 18, 2022, to allow for final integration of the Medford Branch, elimination of a speed restriction on the Lechmere Viaduct, and other work.

[145] In 2021, the MBTA indicated plans to modify the Heath Street–Brigham Circle section of the E branch with accessible platforms to replace the existing non-accessible stopping locations.