Jamestown is a city in southern Chautauqua County, New York, United States. The population was 31,146 at the 2010 census and was estimated at 29,315 in 2018. Situated between Lake Erie to the north and the Allegheny National Forest to the south, Jamestown is the largest population center in the county. Nearby Chautauqua Lake is a freshwater resource used by fishermen, boaters and naturalists.