There are 11 US Post Offices in Shelby County serving a total of 46,979 residents equating to 4,271 residents per post office. It's estimated that approximately 74,984 packages are handled across the 11 county post offices annually. Shelby County is a county located in the U.S. state of Ohio. As of the 2010 census, the population was 49,423. Its county seat is Sidney. Its name honors Isaac Shelby, former governor of Kentucky. Shelby County comprises the Sidney, OH Micropolitan Statistical Area, which is also included in the Dayton-Springfield-Sidney, OH Combined Statistical Area."