Charleston is the most populous city in the U.S. state of South Carolina, the county seat of Charleston County, and the principal city in the Ch…Charleston is the most populous city in the U.S. state of South Carolina, the county seat of Charleston County, and the principal city in the Charleston metropolitan area. The city lies just south of the geographical midpoint of South Carolina's coastline on Charleston Harbor, an inlet of the Atlantic Ocean formed by the confluence of the Ashley, Cooper, and Wando rivers. Charleston had a population of 150,227 at the 2020 census. The population of the Charleston metropolitan area, comprising Berkeley, Charleston, and Dorchester counties, was estimated to be 849,417 in 2023. It ranks as the third-most populous metropolitan statistical area in the state, and the 71st-most populous in the United States.