As of the census of 2000, there were 89,605 people, 34,123 households, and 22,521 families residing in the county. The population density was 108 people per square mile (42/km²). There were 37,250 housing units at an average density of 45 per square mile (17/km²). The racial makeup of the county was 96.87% White, 1.57% Black or African American, 0.08% Native American, 0.74% Asian, 0.01% Pacific Islander, 0.16% from other races, and 0.58% from two or more races. 0.51% of the population were Hispanic or Latino of any race. 25.9% were of German, 11.6% Italian, 10.7% Irish, 8.6% American, 7.1% English and 6.8% Polish ancestry according to Census 2000.
There were 34,123 households out of which 27.90% had children under the age of 18 living with them, 54.30% were married couples living together, 8.20% had a female householder with no husband present, and 34.00% were non-families. 26.50% of all households were made up of individuals and 11.80% had someone living alone who was 65 years of age or older. The average household size was 2.47 and the average family size was 2.99.
In the county, the population was spread out with 21.10% under the age of 18, 16.60% from 18 to 24, 24.80% from 25 to 44, 22.70% from 45 to 64, and 14.90% who were 65 years of age or older. The median age was 36 years. For every 100 females there were 94.00 males. For every 100 females age 18 and over, there were 90.60 males.