There are 2 US Post Offices in Montmorency County serving a total of 7,303 residents equating to 3,652 residents per post office. It's estimated that approximately 11,656 packages are handled across the 2 county post offices annually. Montmorency County is a county located in the U.S. state of Michigan. As of the 2010 census, the population was 9,765. The county seat is Atlanta."