There are 11 US Post Offices in Clay County serving a total of 59,279 residents equating to 5,389 residents per post office. It's estimated that approximately 94,616 packages are handled across the 11 county post offices annually. Clay County is a county located in the U.S. state of Minnesota. As of the 2010 census, the population was 58,999. Its county seat is Moorhead. The county's name is in honor of American statesman Henry Clay, member of the United States Senate from Kentucky and United States Secretary of State in the 19th century. The county was formed in 1862 and organized in 1872. It was originally called Breckenridge County, but changed to its current name in 1862. Clay County is part of the Fargo, ND-MN Metropolitan Statistical Area."