Durham is a town in Middlesex County, Connecticut, United States. Durham is a former farming village on the Coginchaug River in central Connecticut. The town is part of the Lower Connecticut River Valley Planning Region. The population was 7,152 at the 2020 census. Every autumn, the town hosts the Durham Fair, the largest volunteer agricultural fair in New England. The Durham town center is listed by the U.S. Census Bureau as a census-designated place.