As of the census of 2000, there were 42,695 people, 16,540 households, and 9,411 families residing in the county. The population density was 137 people per square mile (53/km²). There were 23,155 housing units at an average density of 74 per square mile (29/km²). The racial makeup of the county was 96.45% White, 1.59% Black or African American, 0.25% Native American, 0.59% Asian, 0.04% Pacific Islander, 0.45% from other races, and 0.62% from two or more races. 1.46% of the population were Hispanics or Latinos of any race.
There were 16,540 households out of which 23.20% had children under the age of 18 living with them, 47.40% were married couples living together, 6.80% had a female householder with no husband present, and 43.10% were non-families. 28.60% of all households were made up of individuals and 8.00% had someone living alone who was 65 years of age or older. The average household size was 2.26 and the average family size was 2.80.
The age distribution is 16.30% under the age of 18, 27.80% from 18 to 24, 23.40% from 25 to 44, 21.50% from 45 to 64, and 11.00% who were 65 years of age or older. The median age was 30 years. The overall age distribution and median age are greatly affected by the presence of Appalachian State University in Boone. For every 100 females there are 99.30 males. For every 100 females age 18 and over, there were 98.20 males.
The median income for a household in the county was $32,611, and the median income for a family was $45,508. Males had a median income of $29,135 versus $22,006 for females. The per capita income for the county was $17,258. About 7.20% of families and 17.90% of the population were below the poverty line, including 11.50% of those under age 18 and 10.60% of those age 65 or over.
No commercial airports or passenger train depots are nearby. A helipad is in service at the Watauga Medical Center. A small general aviation airstrip is located in Boone. Commercial airline passengers typically utilize the airports at Charlotte or Greensboro in North Carolina, or Tri-Cities in Tennessee. Some visitors use Raleigh-Durham International Airport, which may have lower airfares on some routes, but is a considerable distance away.