The highest ground inside the Blue Line that isn't Forest Preserve and isn't under a conservation easement (easements carry public access, so they don't count). Each spot is at least 50 m inside the private parcel, so a boundary slicing across a summit doesn't count.
Elevations from the AWS Terrarium DEM (about 7 m cells), land from the APA State Land Map and DEC easements, each spot checked against DEC's own lands layer. Owners from county tax parcels (NYS parcel service for Warren and Hamilton, Essex and Clinton County GIS).