There are 7 US Post Offices in Winnebago County serving a total of 12,108 residents equating to 1,730 residents per post office. It's estimated that approximately 19,326 packages are handled across the 7 county post offices annually. Winnebago County is a county located in the U.S. state of Iowa. As of the 2010 census, the population was 10,866. The county seat is Forest City. The county was founded in 1847 and named after the Native American tribe. It is the location of the motor homes manufacturer Winnebago Industries."