The county was named for General Francis Marion of South Carolina.
[3] Marion County is included in the Columbus, GA-AL metropolitan statistical area.
[4] The southern half of Marion County, roughly south of Buena Vista, is located in the Kinchafoonee-Muckalee sub-basin of the ACF River Basin (Apalachicola-Chattahoochee-Flint River Basin).
The northwestern portion of the county is located in the Middle Chattahoochee River-Walter F. George Lake sub-basin of the same ACF River Basin.
[5] As of the 2020 United States census, there were 7,498 people, 3,408 households, and 2,396 families residing in the county.