According to the U.S. Census Bureau, the county has a total area of 2,476 km² (956 mi²). 2,460 km² (950 mi²) of it is land and 16 km² (6 mi²) of it is water. The total area is 0.66% water.
As of the census2 of 2000, there are 157,715 people, 60,151 households, and 39,459 families residing in the county. The population density is 64/km² (166/mi²). There are 64,330 housing units at an average density of 26/km² (68/mi²). The racial makeup of the county is 88.00% White, 2.24% Black or African American, 1.25% Native American, 1.54% Asian, 0.53% Pacific Islander, 4.26% from other races, and 2.17% from two or more races. 8.20% of the population are Hispanic or Latino of any race.
There are 60,151 households out of which 32.50% have children under the age of 18 living with them, 52.30% are married couples living together, 9.40% have a female householder with no husband present, and 34.40% are non-families. 25.80% of all households are made up of individuals and 7.10% have someone living alone who is 65 years of age or older. The average household size is 2.52 and the average family size is 3.07.
In the county the population is spread out with 25.00% under the age of 18, 15.30% from 18 to 24, 30.20% from 25 to 44, 19.50% from 45 to 64, and 9.90% who are 65 years of age or older. The median age is 31 years. For every 100 females there are 100.40 males. For every 100 females age 18 and over, there are 98.70 males.
The median income for a household in the county is $34,691, and the median income for a family is $42,795. Males have a median income of $29,428 versus $21,769 for females. The per capita income for the county is $17,347. 14.60% of the population and 9.40% of families are below the poverty line. Out of the total people living in poverty, 16.50% are under the age of 18 and 10.20% are 65 or older.