There are 13 US Post Offices in Clay County serving a total of 10,148 residents equating to 781 residents per post office. It's estimated that approximately 16,197 packages are handled across the 13 county post offices annually. Clay County is a county located in the U.S. state of West Virginia. As of the 2010 census, the population was 9,386. Its county seat is Clay. The county was founded in 1858 and is named in honor of Henry Clay, famous American statesman, member of the United States Senate from Kentucky and United States Secretary of State in the 19th century. Clay County is part of the Charleston, WV Metropolitan Statistical Area."