There are 8 US Post Offices in Watonwan County serving a total of 11,544 residents equating to 1,443 residents per post office. It's estimated that approximately 18,426 packages are handled across the 8 county post offices annually. Watonwan County is a county located in the U.S. state of Minnesota. As of the 2010 census, the population was 11,211. Its county seat is St. James. The county was organized in 1860, two years after Minnesota was granted statehood."