The route starts on the N5 Swinford bypass at Kilbride, a kilometre east of the town centre, picking up a part of the N5's original route into Swinford itself. It heads out of town on a generally west-by-north-westerly bearing, passing Callow Loughs about two-thirds of the way along the 14 km run to Foxford. Here we bear right after crossing the River Moy, and the direction of the remainder of our route is now more northerly as we follow the left bank of the river as it flows down towards Ballina, where our route ends on the N59.
The route was accorded national primary status, and given its present number, in 1994. Before that, it had been the N57 and – earlier still, in the old road classification system – a part of the T77 (from Swinford to Foxford) and T40 (from Foxford to Ballina).