Port Leyden is a village in Lewis County, New York, United States. The population was 665 at the 2000 census. The name is derived from the village's early history as a port on the Black River Canal. The Village of Port Leyden is wholly within the Black River Valley and is mostly in the Town of Leyden; however, a portion of the village lies to the east of the Black River in the Town of Lyonsdale. The village is 17 miles south of Lowville (the county seat), 6 miles north of Boonville, and 23 miles west-south-west of Old Forge.