Berwick is a town in York County, Maine, United States, situated in the southern part of the state beside the Salmon Falls River. Today's South Berwick was set off from Berwick in 1814, while North Berwick was partitioned from the town in 1831. The population was 7,950 at the 2020 census. It is part of the Portland–South Portland–Biddeford, Maine metropolitan statistical area.