Route 23 is a state highway in the northern part of New Jersey, United States. The route runs 52.63 mi (84.70 km) from County Route 506 and County Route 577 in Verona, Essex County northwest to the border with New York at Montague Township in Sussex County, where the road continues to Port Jervis, New York, as Orange County Route 15. Route 23 heads through Essex and Passaic Counties as a two- to four-lane surface road and becomes a six-lane freeway north of a complex interchange with U.S. Route 46 and Interstate 80 in Wayne. The freeway carries Route 23 north to a concurrency with U.S. Route 202. Past the freeway portion, the route heads northwest along the border of Morris and Passaic Counties as a four- to six-lane arterial road with a wide median at places, winding through mountainous areas and crossing Interstate 287 in Riverdale. The route continues northwest through Sussex County as a mostly two-lane surface road that passes through farmland and woodland as well as the communities of Franklin, Hamburg, and Sussex before reaching the New York state line, just south of an interchange with Interstate 84 and US 6 in Port Jervis, in Montague Township near High Point State Park.

County Route 506 is a county highway in the U.S. state of New Jersey. The highway extends 10.78 miles (17.35 km) from Oak Road in Fairfield to Route 7 at the Passaic River in Belleville.