At the intersection with the latter, CR 518 runs east along the border between East Amwell Township, Hunterdon County to the north and Hopwell Township, Mercer County to the south, passing through wooded areas as it crosses fully into Hopewell Township again. 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. At the intersection with CR 654, the route turns east onto Broad Street and passes homes and businesses, intersecting the northern terminus of CR 569 (Princeton Avenue). The road leaves Hopewell Borough for Hopewell Township again, heading northeast into agricultural areas.