According to the 2000 census, the county has a total area of 654.50 square miles (1,695.1 km2), of which 653.01 square miles (1,691.3 km2) (or 99.77%) is land and 1.49 square miles (3.9 km2) (or 0.23%) is water. It is one of four counties in the state with no natural lakes.
There were 47,807 households out of which 35.20% had children under the age of 18 living with them, 56.70% were married couples living together, 8.00% had a female householder with no husband present, and 32.40% were non-families. 25.80% of all households were made up of individuals and 7.60% had someone living alone who was 65 years of age or older. The average household size was 2.53 and the average family size was 3.09.
In the county the population was spread out with 27.00% under the age of 18, 8.50% from 18 to 24, 32.20% from 25 to 44, 21.60% from 45 to 64, and 10.80% who were 65 years of age or older. The median age was 35 years. For every 100 females there were 96.60 males. For every 100 females age 18 and over, there were 93.60 males.
The median income for a household in the county was $51,316, and the median income for a family was $61,610. Males had a median income of $40,196 versus $29,994 for females. The per capita income for the county was $24,939. About 3.80% of families and 6.40% of the population were below the poverty line, including 6.70% of those under age 18 and 9.50% of those age 65 or over.