The Boston & Lowell Railroad started freight operations in 1835, with traffic from the Lowell mills to the Boston port. Demand for the express passenger service exceeded expectations, and in 1842 local service was added as well. The line north of Lowell was first owned by the Boston, Concord & Montreal Railroad, which was chartered in 1844. Trackage was completed as far as Wells River, Vermont, in 1853. The Boston & Maine Railroad acquired the railroad in 1895. The line served as the route for Boston to Montreal service during the Golden Age of Rail. The Ambassador, the train from Boston's North Station to Montreal, ran through Concord, New Hampshire, along this line until 1966. This line, along with the New Englander, via Concord, White River Junction, Montpelier, ran through the northwestern section of Vermont prior to entering Quebec, Canada. The Alouette and Red Wing trains travelled to Montreal via Concord, Plymouth, Wells River and Newport in northeastern Vermont prior to entering Quebec. For this itinerary the Montreal route was marketed as an Air-line railroad. B&M passenger service to Boston on the line was shortened from Concord, New Hampshire to Lowell in 1967. In 1973, the MBTA bought the Lowell line, along with the Haverhill and all other local Greater Boston passenger lines. Along with the sale, the B&M contracted to run the passenger service on the Lowell line for the MBTA. After bankruptcy, the B&M continued to run and fulfill its commuter rail contract under the protection of the United States Bankruptcy Court, in the hopes that a reorganization could make it profitable again. It emerged from the court's protection when newly formed Guilford Transportation Industries purchased it in 1983. For approximately thirteen months in 1980-81, daily passenger service was provided to Concord. Two round-trips were operated on each weekday and one on weekend days. Originally, there were intermediate stops in Manchester and Nashua. A stop in Merrimack was added later. Service was discontinued when federal funding was withdrawn. Anderson Regional Transportation Center opened on April 28, 2001, replacing Mishawum as the Lowell Line's primary park-and-ride station for Route 128. Mishawum was reduced to limited reverse-peak service. On December 15, 2001, the Amtrak Downeaster began operating over the line south of Wilmington. In October 2006, the MBTA added four short turn round trips that terminated at Anderson RTC. The line was shut down on weekends in July through September 2017 for the installation of Positive Train Control equipment in order to meet a 2020 federal deadline.
Expansions
As of 2011, there is a current debate over whether or not to expand the Lowell line to Nashua, New Hampshire and include stations in North Chelmsford and Tyngsborough en route, for the sake of commuters in those towns. In October 2010, the New Hampshire Department of Transportation received a $2.24 million federal grant to study an extension of the Lowell Line to Concord. In January 2011, a bill was introduced into the New Hampshire legislature to end the proposed extension and give up a potential $4.1 million grant into its planning. The MBTA acquired trackage rights from Pan Am in May 2011 as part of a larger transaction. The MBTA is currently building the Green Line Extension through Somerville and part of Medford. One branch of the Extension will follow the right of way of the Lowell Line into Medford. Several stations once existed along that section of the line, but none are in operation any longer.
Operations
Track speeds
North of Wilmington, the line is authorized for a maximum of. South of Wilmington, the line has an unusual asymmetrical speed limit. The northbound track supports up to where curvature allows, while the southbound track has a maximum of. Additional speed restrictions are in place at Wilmington, through the grade crossings in West Medford, and in the North Station terminal area.
Other services
's Downeaster service to Maine, along with some Haverhill Lineexpress trains, run on the Lowell Line from North Station to Wilmington, then follow the Wildcat Branch to the Haverhill Line. This routing is used to avoid the inner Haverhill Line, which has a number of single-track sections. The line is the designated freight clearance route into Boston from the north; all stations with high-level platforms must either have mini-high platforms or a freight passing track. Pan Am Railways runs freight on the line, including local freights based out of Lawrence Yard and DOBO.
