There are 8 US Post Offices in Shelby County serving a total of 11,501 residents equating to 1,438 residents per post office. It's estimated that approximately 18,357 packages are handled across the 8 county post offices annually. Shelby County is a county located in the U.S. state of Iowa. As of the 2010 census, the population was 12,167. The county seat is Harlan. Its name is in honor of Isaac Shelby, the first Governor of Kentucky."