Houston County has no relationship with the city of Houston, which is located approximately 150 miles (260 km) to the south, in Harris County.
As of the census of 2000, there were 23,185 people, 8,259 households, and 5,756 families residing in the county. The population density was 19 people per square mile (7/km²). There were 10,730 housing units at an average density of 9 per square mile (3/km²). The racial makeup of the county was 68.57% White, 27.93% Black or African American, 0.26% Native American, 0.25% Asian, 0.06% Pacific Islander, 2.17% from other races, and 0.76% from two or more races. 7.50% of the population were Hispanic or Latino of any race.
There were 8,259 households out of which 28.70% had children under the age of 18 living with them, 51.90% were married couples living together, 14.20% had a female householder with no husband present, and 30.30% were non-families. 27.90% of all households were made up of individuals and 15.10% had someone living alone who was 65 years of age or older. The average household size was 2.44 and the average family size was 2.97.
In the county, the population was spread out with 23.20% under the age of 18, 6.80% from 18 to 24, 27.70% from 25 to 44, 24.30% from 45 to 64, and 18.00% who were 65 years of age or older. The median age was 40 years. For every 100 females there were 114.10 males. For every 100 females age 18 and over, there were 115.90 males.
The median income for a household in the county was $28,119, and the median income for a family was $35,033. Males had a median income of $29,143 versus $19,885 for females. The per capita income for the county was $14,525. About 15.60% of families and 21.00% of the population were below the poverty line, including 28.30% of those under age 18 and 18.20% of those age 65 or over.
The TTC-69 component (recommended preferred) of the planned Trans-Texas Corridor goes through Houston County .