In 1895 the Nashua & Acton Railroad (formerly the Nashua, Acton & Boston Railroad) came under the control of the Boston & Maine Railroad (B&M) when it took over The Concord & Montreal Railroad. Ownership of the line formally came under the B&M in 1906.
Passenger service on the line was discontinued in 1924 and since the branch didn't have much other traffic, the Boston & Maine sought for abandonment. Until abandonment was approved, the B&M continued occasional freight service until 1926. During the last few days of the branch's existence, a string of ancient boxcars were located on a siding in East Littleton needed to be moved to Nashua to be scrapped. A crew of men spent the day repairing the cars so they could be moved safely, and then it took another day just to get the train from East Littleton to Nashua. Right up until the last train movement on the line, the Acton branch lived up to its financially appropriate nickname, the "red line".
A portion of the branchline remained in Nashua until the 1980s serving local industries, but today not an inch remains. Because the Acton Branch was one of the earliest line's abandoned, within Nashua urban development has encroached on the right of way. A small section in Nashua and in Dunstable has been preserved for trail usage, but otherwise vegetation has reclaimed much of the line.
On a foggy December 1, 1899, Boston & Maine mixed train No. 161 left Nashua midday for Concord Junction in Massachusetts. The train had just stopped at Otterson Street station in Nashua, dropping off a few passengers. The train then proceeded as usual, to a "know-nothing" stop just past Sandy Pond where a fairly decent downgrade section starts as the rail line passed alongside Salmon Brook. When the engineer stopped the train, a moment later he felt the train buck, finding out that half his train had separated at near the station and that it had rolled freely behind the train. When the second half caught up to the rest of the train, the impact threw the brakeman off of a flatcar onto the tracks. The flatcar, partially loaded, snapped from the force of the impact and the boxcar behind it rode up onto the flatcar. The brakeman was run over and crushed to death. The cause of the accident was pointed to a link and pin drawbar being broken when the train started up on a Delaware & Hudson Railroad hopper car loaded with coal.