Hounsfield is a town in Jefferson County, New York, United States. The population was 3,466 at the 2010 census. The name of the town is fr…Hounsfield is a town in Jefferson County, New York, United States. The population was 3,466 at the 2010 census. The name of the town is from Ezra Hounsfield, a land agent and land owner. Hounsfield is in the western part of the county and is west of Watertown.