There are 7 US Post Offices in Iron County serving a total of 11,760 residents equating to 1,680 residents per post office. It's estimated that approximately 18,770 packages are handled across the 7 county post offices annually. Iron County is a county located in the Upper Peninsula of the U.S. state of Michigan. As of the 2010 census, the population was 11,817. The county seat is Crystal Falls."