2000 20,293 1990 20,488 1980 21,302 1970 19,329 1960 16,792 1950 15,047 1940 15,527 1930 15,301 1920 18,736 1910 22,730 1900 27,528 1890 25,932 1880 13,485 1870 8,544 1860 4,945 1850 1,766 1840 1,034 1830 161
As of the census of 2000, there were 20,293 people, 7,773 households, and 5,689 families residing in the county. The population density was 49 people per square mile (19/km²). There were 8,478 housing units at an average density of 20 per square mile (8/km²). The racial makeup of the county was 95.85% White, 0.96% Black or African American, 0.29% Native American, 0.15% Asian, 0.01% Pacific Islander, 1.41% from other races, and 1.33% from two or more races. 3.02% of the population were Hispanic or Latino.
There were 7,773 households out of which 34.10% had children under the age of 18 living with them, 60.90% were married couples living together, 8.10% had a female householder with no husband present, and 26.80% were non-families. 23.00% of all households were made up of individuals and 10.30% 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 3.06.
In the county, the population was spread out with 26.80% under the age of 18, 8.60% from 18 to 24, 28.00% from 25 to 44, 24.00% from 45 to 64, and 12.60% who were 65 years of age or older. The median age was 36 years. For every 100 females there were 96.70 males. For every 100 females age 18 and over, there were 95.40 males.
The median income for a household in the county was $40,327, and the median income for a family was $45,481. Males had a median income of $35,809 versus $21,965 for females. The per capita income for the county was $18,062. About 4.90% of families and 7.70% of the population were below the poverty line, including 9.50% of those under age 18 and 7.10% of those age 65 or over.