Clay County is located in the U.S. state of Missouri and is part of the Kansas City metropolitan area. As of the 2020 census, the county had a population of 253,335, making it the fifth-most populous county in Missouri. Its county seat is Liberty. The county was organized January 2, 1822, and named in honor of U.S. Representative Henry Clay from Kentucky, later a member of the United States Senate and United States Secretary of State.