As of the census of 2000, there were 15,802 people, 6,170 households, and 4,288 families residing in the county. The population density was 17 people per square mile (7/km²). There were 7,112 housing units at an average density of 8 per square mile (3/km²). The racial makeup of the county was 78.45% White, 4.68% Black or African American, 0.49% Native American, 0.24% Asian, 0.06% Pacific Islander, 14.02% from other races, and 2.07% from two or more races. 28.04% of the population were Hispanic or Latino of any race.
There were 6,170 households out of which 32.20% had children under the age of 18 living with them, 53.00% were married couples living together, 12.60% had a female householder with no husband present, and 30.50% were non-families. 27.10% 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 2.48 and the average family size was 3.01.
In the county, the population was spread out with 27.10% under the age of 18, 8.50% from 18 to 24, 25.40% from 25 to 44, 22.60% from 45 to 64, and 16.40% who were 65 years of age or older. The median age was 37 years. For every 100 females there were 94.70 males. For every 100 females age 18 and over, there were 91.70 males.
The median income for a household in the county was $26,209, and the median income for a family was $32,004. Males had a median income of $28,674 versus $19,335 for females. The per capita income for the county was $14,077. About 18.30% of families and 21.70% of the population were below the poverty line, including 29.50% of those under age 18 and 18.50% of those age 65 or over.