The western terminus is situated at PA 59 in Lafayette Township.

The eastern terminus is located at PA 646 in Keating Township.

The route progresses east to the village of Custer City, where it has a short concurrency with US 219.

After the concurrency with US 219, the route continues southeast to its terminus at PA 646 in the village of Aiken.

The route was signed in December 1962 alongside the creation of PA 321,[2] and has stayed on the same roads since its inception.