The east–west portion of the route largely follows the path of the Union Turnpike, built in the early 19th century to connect the communities of Leominster and Concord.

(A few older east–west directional signs still exist east of Harvard.)

The two routes continue northward, crossing Route 2 at exit 109 (old exit 38), before continuing northward, east of Fort Devens into Ayer.

The two routes head northwestward and cross the Nashua River into the town of Pepperell concurrently.

Once in Pepperell, Route 111 turns northward again, running in roughly the same direction as the river.