There are 7 US Post Offices in Mason County serving a total of 28,050 residents equating to 4,007 residents per post office. It's estimated that approximately 44,771 packages are handled across the 7 county post offices annually. Mason County is a county located in the U.S. state of Michigan. As of the 2010 census, the population was 28,705. The county seat is Ludington. Mason County comprises the Ludington, MI Micropolitan Statistical Area."