York County is a county on the north central border in the U.S. state of South Carolina. As of the 2020 census, the population was 282,090, making it the seventh-most populous county in the state. Its county seat is the city of York, and its most populous community is Rock Hill. One Interstate Highway serves the county, Interstate 77. York County is part of the Charlotte-Concord-Gastonia, NC-SC Metropolitan Statistical Area.