Jamestown is an unincorporated community in Tuolumne County, California, United States. Formerly a California Gold Rush town, Jamestown was designated a California Historical Landmark on March 16, 1949. It is the home of Railtown 1897 State Historic Park and the Sierra Railway, which operates steam passenger trains. For statistical purposes, the United States Census Bureau has defined the community as a census-designated place (CDP). The population was 3,478 at the 2020 census, up from 3,433 at the 2010 census.