As of the census of 2000, there were 25,224 people, 9,595 households, and 6,908 families residing in the county. The population density was 32 people per square mile (12/km²). There were 11,955 housing units at an average density of 15 per square mile (6/km²). The racial makeup of the county was 72.65% White, 19.44% Black or African American, 0.36% Native American, 0.23% Asian, 0.02% Pacific Islander, 5.87% from other races, and 1.44% from two or more races. 9.87% of the population were Hispanic or Latino of any race.
There were 9,595 households out of which 32.40% had children under the age of 18 living with them, 55.10% were married couples living together, 12.90% had a female householder with no husband present, and 28.00% were non-families. 25.40% of all households were made up of individuals and 13.60% had someone living alone who was 65 years of age or older. The average household size was 2.59 and the average family size was 3.08.
In the county, the population was spread out with 26.60% under the age of 18, 8.80% from 18 to 24, 25.80% from 25 to 44, 22.20% from 45 to 64, and 16.60% who were 65 years of age or older. The median age was 37 years. For every 100 females there were 92.40 males. For every 100 females age 18 and over, there were 89.20 males.
The median income for a household in the county was $29,112, and the median income for a family was $34,021. Males had a median income of $26,501 versus $20,280 for females. The per capita income for the county was $15,186. About 14.90% of families and 19.40% of the population were below the poverty line, including 24.70% of those under age 18 and 16.90% of those age 65 or over.
The TTC-69 component (recommended preferred) of the planned Trans-Texas Corridor goes through Shelby County .