There are 2 US Post Offices in Adams County serving a total of 3,408 residents equating to 1,704 residents per post office. It's estimated that approximately 5,440 packages are handled across the 2 county post offices annually. Adams County is a county located in the U.S. state of Iowa. As of the 2010 census, the population was 4,029, making it the least-populated county in Iowa. Its county seat is Corning."