Route 18N was a state highway in New Jersey from 1923 to 1929, when it was renumbered as Route 1 and Route S1A. Route 18-N was defined in 1923 to run "from Hoboken to New York State line by way of Weehawken, West Hoboken, town of Union, North Bergen, Fairview, Ridgefield, Palisade Park, Fort Lee, Englewood-Cliffs, Tenafly and Alpine." The part from Hoboken to Fort Lee was not built or taken over as Route 18-N; it seems to follow the old Bergen Turnpike to Ridgefield and then Route 5 east. Route 18-N's south end was at pre-1927 Route 10, now Route 5.