Alexander County is part of the Hickory–Lenoir–Morganton Metropolitan Statistical Area.
As of the census of 2000, there were 33,603 people, 13,137 households, and 9,747 families residing in the county. The population density was 129 people per square mile (50/km²). There were 14,098 housing units at an average density of 54 per square mile (21/km²). The racial makeup of the county was 92.00% White, 4.63% Black or African American, 0.15% Native American, 1.04% Asian, 1.34% from other races, and 0.84% from two or more races. 2.50% of the population were Hispanic or Latino of any race.
There were 13,137 households out of which 32.80% had children under the age of 18 living with them, 60.50% were married couples living together, 9.40% had a female householder with no husband present, and 25.80% were non-families. 21.90% of all households were made up of individuals and 8.40% had someone living alone who was 65 years of age or older. The average household size was 2.54 and the average family size was 2.95.
In the county the population was spread out with 24.50% under the age of 18, 7.90% from 18 to 24, 31.10% from 25 to 44, 24.60% from 45 to 64, and 11.90% who were 65 years of age or older. The median age was 37 years. For every 100 females there were 99.40 males. For every 100 females age 18 and over, there were 96.70 males.
The median income for a household in the county was $38,684, and the median income for a family was $45,691. Males had a median income of $29,857 versus $21,868 for females. The per capita income for the county was $18,507. About 5.90% of families and 8.50% of the population were below the poverty line, including 10.20% of those under age 18 and 14.60% of those age 65 or over.