Durham is a town in Middlesex County, Connecticut, United States. Durham is a former farming village on the Coginchaug River in central Connecticut. The population was 6,627 at the 2000 census. Every autumn, the town hosts the Durham Fair, the largest volunteer agricultural fair in North America. The Durham town center is listed by the U.S. Census Bureau as a census-designated place in the 2000 census. The core of the town center has also been listed as a historic district on the National Register of Historic Places.