It was built in 1873 as one of a pair of range lights for guiding ships up the river to the city's harbor.

The beacons consist of two lights that are separated in distance and elevation, so that when they are aligned, with one above the other, they provide a bearing.

By 1872 Congress had appropriated funds to establish publicly maintained range lights after one of the previous pair was destroyed in a storm.

[2] The rear light is a brick tower, 53 feet (16 m) in height, located close to Water Street near the Merrimack River Coast Guard Station.

The tower is topped by an eight-sided lens room, which is surrounded by an iron balcony and railing.