There are 7 US Post Offices in Dickinson County serving a total of 16,568 residents equating to 2,367 residents per post office. It's estimated that approximately 26,444 packages are handled across the 7 county post offices annually. Dickinson County is a county located in the U.S. state of Iowa. As of the 2010 census, the population was 16,667. The county seat is Spirit Lake. The county was organized in 1857 and is named in honor of Daniel S. Dickinson, a U.S. Senator for New York. Dickinson County comprises the Spirit Lake, IA Micropolitan Statistical Area."