According to the U.S. Census Bureau, the county has a total area of 4,082 km² (1,576 mi²). 4,001 km² (1,545 mi²) of it is land and 81 km² (31 mi²) of it is water. The total area is 1.98% water.
As of the census2 of 2000, there are 125,834 people, 47,702 households, and 33,868 families residing in the county. The population density is 31/km² (81/mi²). There are 50,360 housing units at an average density of 13/km² (33/mi²). The racial makeup of the county is 93.84% White, 0.28% Black or African American, 0.35% Native American, 4.54% Asian, 0.02% Pacific Islander, 0.26% from other races, and 0.72% from two or more races. 0.78% of the population are Hispanic or Latino of any race.
There are 47,702 households out of which 34.00% have children under the age of 18 living with them, 59.90% are married couples living together, 7.40% have a female householder with no husband present, and 29.00% are non-families. 23.60% of all households are made up of individuals and 9.50% have someone living alone who is 65 years of age or older. The average household size is 2.60 and the average family size is 3.11.
In the county, the population is spread out with 26.80% under the age of 18, 8.20% from 18 to 24, 29.50% from 25 to 44, 22.50% from 45 to 64, and 13.00% who are 65 years of age or older. The median age is 36 years. For every 100 females there are 99.50 males. For every 100 females age 18 and over, there are 97.40 males.
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