After the International Drive interchange, US 206 crosses the Musconetcong River and enters Stanhope, Sussex County. Immediately following the river crossing, the freeway merges with the northern terminus of Route 183 at an interchange on the border between Byram Township to the west and Stanhope to the east. Past Route 183, US 206 continues north as a four-lane divided surface road past development, fully entering Stanhope again before crossing into Byram Township. Upon entering Byram Township, the route becomes a two-lane undivided road. Upon turning northwest, the surroundings become more forested as US 206 crosses a mountain, with the northbound direction gaining a second lane for a distance. There are a few businesses along the road as it runs north past wooded areas near Cranberry Lake and Panther Lake. The route continues into Andover, where it becomes Main Street and passes under the abandoned Lackawanna Cut-Off. US 206 forms a brief concurrency with CR 517 in the commercial downtown area. Past CR 517, US 206 bends northwest and enters Andover Township. Here, the road runs back into forested areas, passing by Whites Pond and running near Kittatinny Valley State Park. After a curve to the north, the route enters a mix of development and rural areas, passing to the west of Newton Airport prior to entering Newton.