2000 40,875 1990 35,728 1980 33,477 1970 28,996 1960 29,716 1950 28,188 1940 27,099 1930 25,416 1920 27,610 1910 28,711 1900 30,982 1890 29,048 1880 30,281 1870 29,133 1860 27,773 1850 25,781 1840 22,269 1830 16,345 1820 12,308 1810 5,766
As of the census of 2000, there were 40,875 people, 15,587 households, and 11,394 families residing in the county. The population density was 74 people per square mile (29/km²). There were 17,583 housing units at an average density of 32 per square mile (12/km²). The racial makeup of the county was 96.88% White, 1.50% Black or African American, 0.24% Native American, 0.32% Asian, 0.04% Pacific Islander, 0.15% from other races, and 0.88% from two or more races. 0.53% of the population were Hispanic or Latino of any race.
There were 15,587 households out of which 34.00% had children under the age of 18 living with them, 58.40% were married couples living together, 10.30% had a female householder with no husband present, and 26.90% were non-families. 23.20% of all households were made up of individuals and 10.60% had someone living alone who was 65 years of age or older. The average household size was 2.60 and the average family size was 3.04.
In the county the population was spread out with 27.00% under the age of 18, 8.50% from 18 to 24, 27.80% from 25 to 44, 22.80% from 45 to 64, and 13.80% who were 65 years of age or older. The median age was 36 years. For every 100 females there were 95.20 males. For every 100 females age 18 and over, there were 92.80 males.
The median income for a household in the county was $35,313, and the median income for a family was $41,091. Males had a median income of $32,541 versus $22,842 for females. The per capita income for the county was $16,521. About 9.00% of families and 11.80% of the population were below the poverty line, including 15.40% of those under age 18 and 11.40% of those age 65 or over.