The city is named for its first settler, North Carolina frontiersman John Weldon, who in 1790 built a log home overlooking the spring which bears his name.
A frontiersman from North Carolina named John Weldon first settled Weldon Spring in 1790. He constructed a log home on high ground overlooking a spring (hence the name Weldon Spring). The spring is still visible, located at the northeast corner of the intersection of Highway 94 and I-64.
As of the census of 2000, there were 5,270 people, 1,880 households, and 1,462 families residing in the city. The population density was 666.0 people per square mile (257.2/km²). There were 1,926 housing units at an average density of 243.4/sq mi (94.0/km²). The racial makeup of the city was 96.00% White, 1.82% African American, 0.15% Native American, 1.08% Asian, 0.04% Pacific Islander, 0.30% from other races, and 0.61% from two or more races. Hispanic or Latino of any race were 1.10% of the population.
There were 1,880 households out of which 35.7% had children under the age of 18 living with them, 73.1% were married couples living together, 3.4% had a female householder with no husband present, and 22.2% were non-families. 20.1% of all households were made up of individuals and 11.9% had someone living alone who was 65 years of age or older. The average household size was 2.66 and the average family size was 3.09.
In the city the population was spread out with 26.6% under the age of 18, 4.2% from 18 to 24, 24.1% from 25 to 44, 29.0% from 45 to 64, and 16.2% who were 65 years of age or older. The median age was 42 years. For every 100 females there were 89.4 males. For every 100 females age 18 and over, there were 85.3 males.
The median income for a household in the city was $87,998, and the median income for a family was $102,516. Males had a median income of $66,522 versus $40,339 for females. The per capita income for the city was $40,810. About 2.6% of families and 4.4% of the population were below the poverty line, including 2.7% of those under age 18 and 12.5% of those age 65 or over.