Douglas County's population was estimated to be 112,123 in the year 2006, an increase of 11,984, or +12.0%, over the previous six years; it has the second fastest growing and fifth largest population in the state (Johnson County has the fastest growing and largest population).
As of the U.S. Census in 2000, there were 99,962 people, 38,486 households, and 21,167 families residing in the county. The population density was 219 people per square mile (84/km²). There were 40,250 housing units at an average density of 88 per square mile (34/km²). The racial makeup of the county was 86.09% White, 4.24% Black or African American, 2.56% Native American, 3.12% Asian, 0.06% Pacific Islander, 1.20% from other races, and 2.73% from two or more races. Hispanic or Latino of any race were 3.27% of the population.
There were 38,486 households out of which 27.40% had children under the age of 18 living with them, 43.10% were married couples living together, 8.50% had a female householder with no husband present, and 45.00% were non-families. 28.50% of all households were made up of individuals and 5.80% had someone living alone who was 65 years of age or older. The average household size was 2.37 and the average family size was 2.97.
In the county the population was spread out with 20.40% under the age of 18, 26.40% from 18 to 24, 28.30% from 25 to 44, 16.90% from 45 to 64, and 7.90% who were 65 years of age or older. The median age was 27 years. For every 100 females there were 98.70 males. For every 100 females age 18 and over, there were 97.70 males.
The median income for a household in the county was $37,547, and the median income for a family was $53,991. Males had a median income of $35,577 versus $27,225 for females. The per capita income for the county was $19,952. About 6.20% of families and 15.90% of the population were below the poverty line, including 9.00% of those under age 18 and 7.30% of those age 65 or over.