There are 8 US Post Offices in Marion County serving a total of 67,006 residents equating to 8,376 residents per post office. It's estimated that approximately 106,949 packages are handled across the 8 county post offices annually. Marion County is a county located in the U.S. state of Ohio. As of the 2010 census, the population was 66,501. Its county seat is Marion. The county was created in 1820 and later organized in 1824. It is named for General Francis \"The Swamp Fox\" Marion, a South Carolinian officer in the Revolutionary War. Marion County comprises the Marion, OH Micropolitan Statistical Area, which is also included in the Columbus-Marion-Zanesville, OH Combined Statistical Area."