As of the 2010 United States Census, there were 21,218 people, 8,601 households, and 6,075 families residing in the county. The population density was 61.6 inhabitants per square mile. There were 12,804 housing units at an average density of 37.2 per square mile. The racial makeup of the county was 67.9% white, 26.0% black or African American, 0.5% Asian, 0.2% American Indian, 0.1% Pacific islander, 4.1% from other races, and 1.2% from two or more races. Those of Hispanic or Latino origin made up 6.3% of the population. In terms of ancestry, 27.2% were American, 26.0% African, 10.7% were Irish, 9.9% were English, and 5.9% were German.
Of the 8,601 households, 29.0% had children under the age of 18 living with them, 51.8% were married couples living together, 14.2% had a female householder with no husband present, 29.4% were non-families, and 24.7% of all households were made up of individuals. The average household size was 2.45 and the average family size was 2.88. The median age was 43.5 years.
The median income for a household in the county was $41,529 and the median income for a family was $49,814. Males had a median income of $31,915 versus $30,857 for females. The per capita income for the county was $25,576. About 9.3% of families and 12.3% of the population were below the poverty line, including 17.0% of those under age 18 and 12.0% of those age 65 or over.