It passes through an area of industrial parks before clipping the northwest corner of North Reading and entering Andover.

The two routes split at a point between Lawrence Municipal Airport and Lake Cochichewick in the northern end of town.

In Bradford, Route 125 meets a connector road between it and I-495 which passes through an industrial area.

The route then continues through the Bradford area before crossing the Merrimack River at the Basiliere Bridge.

Main Street, meanwhile, heads into Plaistow as well, where it meets the end of New Hampshire Route 121.