New Jersey State Route 15 is a north-south highway in Morris County. It runs from U.S. Rt. 46, at Dover, to the Morris/Sussex County Line, near Sparta Township. NJ St Rt 15 passes through the following towns in Morris County. Dover Wharton NJ St Rt 15 is not multi-plexed in Morris County. NJ St Rt 15 intersects the following highways in Morris County. U.S. Rt. 46, at Dover. Interstate 80, at Wharton. New Jersey State Route 181, near Lake Hopatcong.