Jamestown is a city in southern Chautauqua County, New York, United States. The population was 28,712 at the 2020 census. Situated between Lake Erie to the north and the Allegheny National Forest to the south, Jamestown is the largest city in the county. Nearby Chautauqua Lake is a freshwater resource used by fishermen, boaters, and naturalists. In the 20th century, Jamestown was a thriving industrial area, noted for producing several well-known products.