The Nashua and Lowell Railroad (N&L) was a 14-mile-long (23 km) railroad built to connect Nashua, New Hampshire with the city of Lowell, Massachusetts. Chartered in June 1835, construction began in 1837 and the first train ran the next year. The Nashua and Lowell was the first railroad built in the state of New Hampshire.
The company was quickly successful, with large volumes of freight and passengers traveling its line; as a result, the route was double tracked in 1848. Operations were run jointly with the Boston and Lowell Railroad (B&L) from 1857 to 1878 as a railroad pool. Following the dissolution of this agreement, the N&L returned to independent operations until 1880, when the Boston and Lowell Railroad leased the entire line. The Boston and Lowell was in turn leased by the Boston and Maine Railroad (B&M) in 1887; the Nashua and Lowell continued to exist on paper until it was formally purchased by the B&M in 1944