The Dorchester and Milton Branch Railroad was a railroad in Massachusetts. It was incorporated in 1846 as a branch off the Old Colony Railroad main line from Boston to Plymouth. The 3.3 mile road was completed on December 1, 1847 from Neponset Village in Dorchester, Massachusetts through the town of Milton to the village of Mattapan. The line was leased to the Old Colony Railroad from January 1, 1848 to January 1, 1856, and operated under contract by the Old Colony from 1856 to 1863 when it was merged into the Old Colony and Fall River Railroad Company. In 1893, it became part of the New York, New Haven and Hartford Railroad as part of the lease of the entire Old Colony Railroad network. From 1848 to 1872, commuter rail service to Ashmont operated over the whole line. When the Shawmut Branch opened in 1872, Mattapan commuter service was diverted over the new line, and the Milton Branch east of Shawmut Junction saw little passenger traffic. After the Shawmut Branch was closed on September 6, 1926 for construction of the Dorchester Extension, all Mattapan passenger and freight service was rerouted via Neponset over the Milton Branch. Local residents lobbied for the restoration of a flag stop at the Granite Avenue station to serve the Cedar Grove and Ashmont neighborhoods, a request granted in October 1926. The first section of the Ashmont-Mattapan High Speed Line opened from Ashmont to Milton on August 26, 1929. The high-speed trolley line entered the center of the Milton Branch right of way on a flyover, and ran to Milton flanked by the Milton Branch tracks. Commuter rail service ended when the trolley line reached Milton, over the protests of Milton residents who wanted limited service kept while the trolley line was extended to Mattapan. After four more months of construction, the full trolley line was opened to Mattapan on December 21, 1929. Freight service was retained on the line as far as Milton until the 1980s. The Neponset Trail, a multi-use rail trail, was later built on the right-of-way from Neponset Avenue to Central Avenue. From Shawmut Junction to Central Avenue, it shares the corridor with the MBTA trolley line, and occupies only the former northern freight track. An extension of the trail to Mattapan, largely parallel to the line rather than adjacent to it, opened in 2017.
