There are 3 US Post Offices in Gladwin County serving a total of 26,617 residents equating to 8,872 residents per post office. It's estimated that approximately 42,484 packages are handled across the 3 county post offices annually. Gladwin County is a county located in the U.S. state of Michigan. As of the 2010 census, the population was 25,692. The county seat is Gladwin."