There are 5 US Post Offices in Copiah County serving a total of 31,528 residents equating to 6,306 residents per post office. It's estimated that approximately 50,322 packages are handled across the 5 county post offices annually. Copiah County is a county located in the U.S. state of Mississippi. As of the 2010 census, the population was 29,449. The county seat is Hazlehurst. With an eastern border formed by the Pearl River, Copiah County is part of the Jackson, MS Metropolitan Statistical Area."