As of the census[2] of 2000, there were 88,969 people, 31,674 households, and 19,954 families residing in the county. The population density was 140 people per square mile (54/km²). There were 32,988 housing units at an average density of 52 per square mile (20/km²). The racial makeup of the county was 88.46% White, 4.59% Black or African American, 0.22% Native American, 2.35% Asian, 0.07% Pacific Islander, 2.74% from other races, and 1.57% from two or more races. 6.55% of the population were Hispanic or Latino of any race. 25.6% were of German, 10.8% Irish, 7.2% English, 5.9% American and 5.0% Norwegian ancestry according to Census 2000. 90.8% spoke English and 5.7% Spanish as their first language.

There were 31,674 households out of which 32.50% had children under the age of 18 living with them, 50.90% were married couples living together, 8.50% had a female householder with no husband present, and 37.00% were non-families. 25.50% of all households were made up of individuals and 7.90% 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 3.11.

In the county the population was spread out with 23.10% under the age of 18, 22.00% from 18 to 24, 27.60% from 25 to 44, 17.40% from 45 to 64, and 9.80% who were 65 years of age or older. The median age was 28 years. For every 100 females there were 98.20 males. For every 100 females age 18 and over, there were 96.50 males.

The median income for a household in the county was $45,828, and the median income for a family was $58,194. Males had a median income of $41,111 versus $26,690 for females. The per capita income for the county was $19,462. About 5.10% of families and 11.40% of the population were below the poverty line, including 7.10% of those under age 18 and 4.50% of those age 65 or over.