There are 10 US Post Offices in Champaign County serving a total of 39,651 residents equating to 3,965 residents per post office. It's estimated that approximately 63,287 packages are handled across the 10 county post offices annually. Champaign County is a county located in the U.S. state of Ohio. As of the 2010 census, the population was 40,097. Its county seat is Urbana. The county takes its name from the French word for \"open level country\". Champaign County comprises the Urbana, OH Micropolitan Statistical Area, which is also included in the Dayton-Springfield-Sidney, OH Combined Statistical Area."