There are 4 US Post Offices in Otsego County serving a total of 23,699 residents equating to 5,925 residents per post office. It's estimated that approximately 37,826 packages are handled across the 4 county post offices annually. Otsego County is a county located in the U.S. state of Michigan. As of the 2010 census, the population was 24,164. The county seat is Gaylord. The county was founded in 1840 and organized in 1875."