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. The county is served by one Interstate Highway, Interstate 77.

Rock Hill is the most populous city in York County, South Carolina, United States, and the 5th-most populous city in the state. It is also the 4th-most populous city of the Charlotte metropolitan area, behind Charlotte, Concord, and Gastonia. As of the 2020 census, the city's population was 74,372.