There are 7 US Post Offices in Marion County serving a total of 19,423 residents equating to 2,775 residents per post office. It's estimated that approximately 31,001 packages are handled across the 7 county post offices annually. Marion County is a county in the U.S. state of Kentucky. As of the 2010 census, the population was 19,820. Its county seat is Lebanon. The county was founded in 1834 and named for Francis Marion."