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.

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 textile industry in Nashua, 14 miles (23 km) from Lowell, was rapidly growing, fueling demand for a railroad to be built.

The railroad's backers convinced the Massachusetts legislature to grant a charter for the remaining 9 miles (14 km) to Lowell in April 1836.

[2] Construction was greatly aided by level terrain: the steepest slope on the entire route was a change in elevation of 20 feet (6 m) over a mile.

[3] The Nashua Daily Telegraph commented that the gathering of the requisite funds for the railroad's construction "was at that time a matter calling for ... real financial courage.

In 1848, the company agreed to operate the Stony Brook Railroad, which was approaching completion of construction between North Chelmsford and Ayer.

A return of passenger service by MBTA Commuter Rail was briefly attempted in 1980, before being suspended in February 1981 due to low ridership.

[1] After going bankrupt in the 1970s, the Boston and Maine was purchased by Guilford Transportation Industries in 1983, which became the new tenant of the former Nashua and Lowell trackage.