Marion County is a
county located in the northeastern portion of the
U.S. state of
Missouri. As of the
2010 census, the population was 28,781. Its
county seat is
Palmyra. Unique from most third class counties in the state Marion has two courthouses, the second located in
Hannibal. The county was organized December 23, 1826 and named for General
Francis Marion, the "Swamp Fox," who was from South Carolina and served in the
American Revolutionary War. The area was known as the "Two Rivers Country" before organization.