There are 9 US Post Offices in Sumter County serving a total of 14,193 residents equating to 1,577 residents per post office. It's estimated that approximately 22,654 packages are handled across the 9 county post offices annually. Sumter County is a county of the U.S. state of Alabama. As of the 2010 census, the population was 13,763. Its county seat is Livingston. Its name is in honor of General Thomas Sumter of South Carolina."