There are 13 US Post Offices in Polk County serving a total of 45,173 residents equating to 3,475 residents per post office. It's estimated that approximately 72,101 packages are handled across the 13 county post offices annually. Polk County is a county in the U.S. state of Wisconsin. As of the 2010 census, the population was 44,205. Its county seat is Balsam Lake. The county was created in 1853."