There are 9 US Post Offices in Monroe County serving a total of 40,736 residents equating to 4,526 residents per post office. It's estimated that approximately 65,019 packages are handled across the 9 county post offices annually. Monroe County is a county on the northeast border of the U.S. state of Mississippi next to Alabama. As of the 2010 census, the population was 36,989. Its county seat is Aberdeen."