Rocky Hill is a town in Hartford County, Connecticut, United States. The town is part of the Capitol Planning Region. The population was 20,845 at the 2020 census. It was originally land of the Wangunks. Europeans began to settle the area of Rocky Hill in 1650, as part of Wethersfield, the neighboring town to the north. In 1722, the area became known as Stepney Parish, until it was independently incorporated in 1843.