The route heads northward through the town of Orangetown, serving a residential community before entering a more forested area and crossing over the Palisades Interstate Parkway (PIP).

Not far to the north is the densely populated hamlet of Sparkill, where the highway passes Rockland Country Club and John O'Rourke Memorial Park.

Just past the indirect junction with US 9W is an intersection with Ferdon Avenue,[5] where maintenance of NY 340 shifts from NYSDOT to the town of Orangetown.

[6] Just 0.11 miles (0.18 km) northwest of Ferdon Avenue, the route briefly enters the village of Piermont, where it remains locally maintained.

The road was constructed to connect Tappan Landing (current-day Piermont) with then the settlement of Greenbush for purposes of transporting produce.