The road climbs in elevation heading east through wooded residential areas before turning southeast and crossing into West Amwell Township and becoming Brunswick Pike.

CR 518 ascends and descends a spur of the Sourland Mountains before continuing into Hopewell Borough, where it becomes Louellen Street and crosses CSX's Trenton Subdivision before heading into residential areas.

[1][4] At Stoutsburg, CR 518 crosses the Keith line and continues into Montgomery Township, Somerset County, passing farms, woods, and residential subdivisions.

The route ascends Ten Mile Run Mountain and passes through more forests to the north of a quarry, climbing a steep hill, and curves to the northeast, flattening out into a mix of farms, woods, and homes.

[5] Beginning in 2014, Somerset County began reconstruction of a steep, winding section of CR 518 in Franklin Township to reduce the potential for accidents and improve the quality of the road in the area.