 The north–south highway left NY 17 at the hamlet of Ramapo and followed the modern New York State Thruway and I-287 corridors south through Hillburn to the New Jersey state line.In the mid-1930s, the alignments of NY 17 and NY 339 south of Ramapo were swapped, placing NY 17 on the bypass and NY 339 on the Ramapo–Suffern route.In Suffern, NY 339 ended at a junction with US 202 just one block north of NY 59's western terminus.