- Western Terminus:
- NY 303 in Orangeburg
- Eastern Terminus:
- Piermont Road (CR 501) at the New York-New Jersey state line
- 3.17 miles
NY 340 is a short extension of Piermont Road (CR 501) into New York. Despite connecting to a north/south route in New Jersey and running primarily north and south, it is designated an east/west route. It begins at NY 303 and runs southwest to Sparkill, where it comes within one block of US 9W without touching it. It then runs south to the state line, where it becomes Piermont Road (CR 501). The entire length is a two-lane undivided road.