2000 30,707 1990 27,651 1980 26,215 1970 23,395 1960 20,954 1950 18,828 1940 17,001 1930 15,931 1920 15,660 1910 16,892 1900 17,328 1890 17,768 1880 16,941 1870 14,399 1860 10,730 1850 5,190 1840 1,237
As of the census of 2000, there were 30,707 people, 11,711 households, and 8,607 families residing in the county. The population density was 92 people per square mile (35/km²). There were 12,545 housing units at an average density of 37 per square mile (14/km²). The racial makeup of the county was 98.37% White, 0.19% Black or African American, 0.36% Native American, 0.18% Asian, 0.04% Pacific Islander, 0.30% from other races, and 0.57% from two or more races. 0.90% of the population were Hispanic or Latino of any race. 41.7% were of German, 18.8% American, 8.1% English and 7.2% Irish ancestry according to Census 2000.
There were 11,711 households out of which 34.50% had children under the age of 18 living with them, 61.30% were married couples living together, 8.30% had a female householder with no husband present, and 26.50% were non-families. 22.40% of all households were made up of individuals and 9.50% 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 3.03.
In the county the population was spread out with 26.70% under the age of 18, 8.10% from 18 to 24, 28.90% from 25 to 44, 23.20% from 45 to 64, and 13.00% who were 65 years of age or older. The median age was 37 years. For every 100 females there were 98.50 males. For every 100 females age 18 and over, there were 96.00 males.
The median income for a household in the county was $45,503, and the median income for a family was $52,872. Males had a median income of $37,325 versus $23,420 for females. The per capita income for the county was $20,519. About 3.30% of families and 4.90% of the population were below the poverty line, including 5.30% of those under age 18 and 6.20% of those age 65 or over.