New Somerset is an unincorporated community in northern Knox Township, Jefferson County, Ohio, United States. It lies south of Hammondsville along State Route 213, at 40°30′57″N 80°42′21″W. N…New Somerset is an unincorporated community in northern Knox Township, Jefferson County, Ohio, United States. It lies south of Hammondsville along State Route 213, at 40°30′57″N 80°42′21″W. New Somerset is part of the Weirton–Steubenville, WV-OH Metropolitan Statistical Area.