According to the U.S. Census Bureau, the county has a total area of 907 square miles (2,349 km˛), of which, 882 square miles (2,285 km˛) of it is land and 25 square miles (64 km˛) of it (2.72%) is water.
As of the census of 2000, there were 85,897 people, 31,417 households, and 22,306 families residing in the county. The population density was 97 people per square mile (38/km˛). There were 33,672 housing units at an average density of 38 per square mile (15/km˛). The racial makeup of the county was 95.28% White, 2.49% Black or African American, 0.40% Native American, 0.34% Asian, 0.03% Pacific Islander, 0.87% from other races, and 0.58% from two or more races. 2.55% of the population were Hispanic or Latino of any race. 60.9% were of German and 5.0% Irish ancestry according to Census 2000. 95.8% spoke English, 2.2% Spanish and 1.5% German as their first language.
There were 31,417 households out of which 33.90% had children under the age of 18 living with them, 59.60% were married couples living together, 7.50% had a female householder with no husband present, and 29.00% were non-families. 24.10% of all households were made up of individuals and 10.80% had someone living alone who was 65 years of age or older. The average household size was 2.56 and the average family size was 3.05.
In the county, the population was spread out with 24.80% under the age of 18, 8.30% from 18 to 24, 31.20% from 25 to 44, 21.90% from 45 to 64, and 14.00% who were 65 years of age or older. The median age was 37 years. For every 100 females there were 109.70 males. For every 100 females age 18 and over, there were 110.80 males.