There are 3 US Post Offices in Perry County serving a total of 18,559 residents equating to 6,186 residents per post office. It's estimated that approximately 29,622 packages are handled across the 3 county post offices annually. Perry County is a county located in the southeastern portion of the U.S. state of Missouri. As of the 2010 census, the population was 18,971. Its county seat is Perryville. The county was officially organized on November 16, 1820 (effective January 1, 1821) from Ste. Genevieve County and was named after Oliver Hazard Perry, a naval hero of the War of 1812."