The Shawangunk Kill is a 47.2-mile-long (76.0 km) stream that flows northward through Orange, Sullivan and Ulster counties, New York, in the United States. It is the largest tributary of the Wallkill River. It takes its name from the neighboring Shawangunk Ridge, where it rises in the town of Greenville, then flowing down into the valley. For part of its length, it forms the northwestern boundary of Orange County, with first Sullivan and then Ulster County along the other side.