There are 8 US Post Offices in Audrain County serving a total of 23,684 residents equating to 2,961 residents per post office. It's estimated that approximately 37,802 packages are handled across the 8 county post offices annually. Audrain County is a county located in the central part of the U.S. state of Missouri. As of the 2010 Census, the population was 25,529. Its county seat is Mexico. The county was organized December 13, 1836, and named for Colonel James Hunter Audrain of the War of 1812 and who later was elected to the state legislature. Audrain County comprises the Mexico, MO Micropolitan Statistical Area, which is included in the Columbia-Moberly-Mexico, MO Combined Statistical Area."