There are 4 US Post Offices in Waseca County serving a total of 19,485 residents equating to 4,871 residents per post office. It's estimated that approximately 31,100 packages are handled across the 4 county post offices annually. Waseca County is a county located in the U.S. state of Minnesota. As of the 2010 census, the population was 19,136. Its county seat is Waseca."