Marion County is a county located in the U.S. state of Mississippi. As of the 2010 census, the population was 27,088. Its county seat is Columbia. Marion County is named for American Revolutionary War guerrilla leader Francis Marion also known as The Swamp Fox.
According to the U.S. Census Bureau, the county has a total area of 549 square miles (1,420 km), of which 542 square miles (1,400 km) is land and 6.2 square miles (16 km) (1.1%) is water.
As of the census of 2000, there were 25,595 people, 9,336 households, and 6,880 families residing in the county. The population density was 47 people per square mile (18/km²). There were 10,395 housing units at an average density of 19 per square mile (7/km²). The racial makeup of the county was 66.96% White, 31.87% Black or African American, 0.23% Native American, 0.21% Asian, 0.01% Pacific Islander, 0.11% from other races, and 0.62% from two or more races. 0.62% of the population were Hispanic or Latino of any race.
There were 9,336 households out of which 34.80% had children under the age of 18 living with them, 54.00% were married couples living together, 15.60% had a female householder with no husband present, and 26.30% were non-families. 24.20% of all households were made up of individuals and 12.60% had someone living alone who was 65 years of age or older. The average household size was 2.64 and the average family size was 3.13.
In the county, the population was spread out with 27.80% under the age of 18, 9.50% from 18 to 24, 26.90% from 25 to 44, 21.50% from 45 to 64, and 14.30% who were 65 years of age or older. The median age was 35 years. For every 100 females there were 93.70 males. For every 100 females age 18 and over, there were 88.80 males.
The median income for a household in the county was $24,555, and the median income for a family was $29,894. Males had a median income of $26,909 versus $17,192 for females. The per capita income for the county was $12,301. About 20.70% of families and 24.80% of the population were below the poverty line, including 32.60% of those under age 18 and 23.00% of those aged 65 or over.