Grahamsville is a hamlet (and census-designated place)[2] at the junction of NY 42 and 55 in the Town of Neversink, in Sullivan County, New York, United States.

A Department of Environmental Protection branch was built in the heart of the town to increase the security near the Rondout and Neversink Reservoirs.

These reservoirs are part of the water supply for New York City, so it is important that the environment in this region is safe from terrorism and any other kind of threat.

The area was not settled permanently until after the American Revolutionary War due to a reputation for raids by the Native American population (the hamlet takes its name from the leader of a Continental Army unit killed nearby in 1778) and the manorial land ownership system that remained in some areas of the Hudson Valley through the 1840s.

The church and homes in the historic district are what grew up around the western end of a stage road (today part of Route 55) to Wawarsing, nearby to the east in Ulster County.