This county is a part of the Atlanta metropolitan area (Atlanta-Sandy Springs-Marietta, Georgia Metropolitan Statistical Area).
Forbes.com named it as the 13th wealthiest county in the United States for 2008, and the wealthiest county in the state of Georgia.
As of the census of 2000, there were 98,407 people, 34,565 households, and 28,101 families residing in the county. The population density was 436 people per square mile (168/km²). There were 36,505 housing units at an average density of 162 per square mile (62/km²). The racial makeup of the county was 95.05% White, 0.70% Black or African American, 0.25% Native American, 0.80% Asian, 2.01% Pacific Islander, 2.27% from other races, and 0.93% from two or more races. 2.57% of the population were Hispanic or Latino of any race. 21.7% were of American, 14.1% English, 13.0% Irish and 11.8% German ancestry according to Census 2000.
There were 34,565 households out of which 41.70% had children under the age of 18 living with them, 71.90% were married couples living together, 6.60% had a female householder with no husband present, and 18.70% were non-families. 14.80% of all households were made up of individuals and 4.00% had someone living alone who was 65 years of age or older. The average household size was 2.83 and the average family size was 3.12.
The age distribution was 27.90% under the age of 18, 6.10% from 18 to 24, 37.10% from 25 to 44, 21.80% from 45 to 64, and 7.10% who were 65 years of age or older. The median age was 35 years. For every 100 females there were 102.70 males. For every 100 females age 18 and over, there were 100.60 males.
The median income for a household in the county was $68,890, and the median income for a family was $74,003 (these figures had risen to $84,815 and $91,658 respectively as of a 2007 estimate). Males had a median income of $50,862 versus $32,112 for females. The per capita income for the county was $29,114. About 3.90% of families and 5.50% of the population were below the poverty line, including 5.60% of those under age 18 and 10.20% of those age 65 or over.