As of the census of 2000, 20,785 people, 6,140 households, and 4,525 families resided in the county. The population density was 22 people per square mile. The 7,236 housing units averaged 8 per square mile. The racial makeup of the county was 78.80% White, 11.51% Black or African American, 0.49% Native American, 0.47% Asian, 0.01% Pacific Islander, 7.46% from other races, and 1.27% from two or more races. About 20.9% of the population was Hispanic or Latino of any race. Of the 6,140 households, 33.40% had children under the age of 18 living with them, 59.60% were married couplesliving together, 10.10% had a female householder with no husband present, and 26.30% were not families. About 24.1% of all households were made up of individuals, and 13.40% had someone living alone who was 65 years of age or older. The average household size was 2.58 and the average family size was 3.06. In the county, the population was distributed as 22.50% under the age of 18, 11.10% from 18 to 24, 31.50% from 25 to 44, 21.00% from 45 to 64, and 14.00% who were 65 years of age or older. The median age was 36 years. For every 100 females, there were 150.10 males. For every 100 females age 18 and over, there were 159.70 males. The median income for a household in the county was $29,572, and for a family was $35,391. Males had a median income of $26,892 versus $17,829 for females. The per capita income for the county was $13,656. About 13.10% of families and 16.80% of the population were below the poverty line, including 22.70% of those under age 18 and 16.60% of those age 65 or over.
Up until 2000, Jones County was dominated by white conservative members of the Democratic Party, with a political history typical of the Solid South. Racial minorities had been largely disenfranchised from the turn of the 20th century, well into the late 1960s, by laws that discriminated against them and made voter registration and voting more difficult. The majority of voters in the county, who were generally white conservatives, supported Republican presidential candidates only five times from 1912 to 1996. Through the late 20th century, white conservatives shifted into the Republican Party, while minority ethnic groups largely aligned with the Democratic Party, which had supported their campaigns for civil rights. Some Republican candidates also began to win local and state offices. Since 2000, the majority of voters have selected Republican presidential candidates, with the margin of victory for the party's candidates increasing in each election.
