As of the census of 2000, there were 51,731 people, 19,863 households, and 13,884 families residing in the county. The population density was 69 people per square mile (27/km²). There were 22,508 housing units at an average density of 30 per square mile (12/km²). The racial makeup of the county was 97.93% White, 0.17% Black or African American, 0.42% Native American, 0.27% Asian, 0.01% Pacific Islander, 0.54% from other races, and 0.66% from two or more races. 1.38% of the population were Hispanic or Latino of any race. 53.1% were of German, 8.5% Norwegian and 6.8% Irish ancestry according to Census 2000. 96.6% spoke English, 1.4% Spanish and 1.3% German as their first language.
There were 19,863 households out of which 32.60% had children under the age of 18 living with them, 58.40% were married couples living together, 7.40% had a female householder with no husband present, and 30.10% were non-families. 25.20% of all households were made up of individuals and 11.70% had someone living alone who was 65 years of age or older. The average household size was 2.51 and the average family size was 3.01.
In the county, the population was spread out with 25.70% under the age of 18, 7.10% from 18 to 24, 27.80% from 25 to 44, 22.70% from 45 to 64, and 16.70% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 100.30 males. For every 100 females age 18 and over, there were 98.40 males.