There are 5 US Post Offices in Arenac County serving a total of 15,403 residents equating to 3,081 residents per post office. It's estimated that approximately 24,585 packages are handled across the 5 county post offices annually. Arenac County is a county located in the U.S. state of Michigan. As of the 2010 census, the population was 17,269. The county seat is Standish."