King George County is a county located in the Commonwealth of Virginia. As of the 2020 census, the population sits at 26,723. Its county seat is the town of King George. The county's largest employer is the U.S. Naval Surface Warfare Center Dahlgren Division. It is adjacent to the newly built, four-lane, 2-mile-long Harry W. Nice Memorial Bridge carrying U.S. Highway 301 over the Potomac River. It contains the ZIP codes 22448 and 22485.