The Lowell Line is a commuter rail service of the MBTA Commuter Rail system, running north–south between Boston and Lowell, Massachusetts. It is 25.4 miles (40.9 km) long, with nine stations including the terminals at North Station and Lowell station. All stations are accessible except for Mishawum, which has been indefinitely closed since 2020.
Lowell Line service runs on the New Hampshire Main Line, originally built as the Boston and Lowell Railroad in 1835. It was leased by the Boston and Maine Railroad in 1887. Local service operated between Boston and Concord, New Hampshire, with most trains using the Woburn Loop. The final Concord service ended in 1967 during the transition to Massachusetts Bay Transportation Authority subsidization, leaving Lowell–Boston and Woburn–Boston service. Concord service briefly resumed in 1980–81; Woburn service ended in 1981.