2000 21,806 1990 21,512 1980 23,239 1970 23,575 1960 22,572 1950 23,157 1940 22,601 1930 20,846 1920 23,318 1910 24,961 1900 26,818 1890 23,478 1880 19,282 1870 15,000 1860 11,399 1850 7,047 1840 3,863
As of the census of 2000, there were 21,806 people, 8,405 households, and 6,017 families residing in the county. The population density was 57 people per square mile (22/km²). There were 9,074 housing units at an average density of 24 per square mile (9/km²). The racial makeup of the county was 97.64% White, 0.25% Black or African American, 0.17% Native American, 0.34% Asian, 0.02% Pacific Islander, 0.85% from other races, and 0.73% from two or more races. 1.79% of the population were Hispanic or Latino of any race. 32.9% were of American, 28.1% German, 8.8% English and 8.6% Irish ancestry according to Census 2000.
There were 8,405 households out of which 32.30% had children under the age of 18 living with them, 58.80% were married couples living together, 9.10% had a female householder with no husband present, and 28.40% were non-families. 24.80% of all households were made up of individuals and 12.20% had someone living alone who was 65 years of age or older. The average household size was 2.57 and the average family size was 3.06.
In the county the population was spread out with 27.00% under the age of 18, 7.70% from 18 to 24, 27.30% from 25 to 44, 23.30% from 45 to 64, and 14.70% who were 65 years of age or older. The median age was 37 years. For every 100 females there were 96.30 males. For every 100 females age 18 and over, there were 92.50 males.
The median income for a household in the county was $35,700, and the median income for a family was $41,850. Males had a median income of $31,031 versus $21,015 for females. The per capita income for the county was $16,686. About 5.80% of families and 9.10% of the population were below the poverty line, including 12.40% of those under age 18 and 7.90% of those age 65 or over.