Like many incorporated towns in Virginia, the town of Warrenton has government and taxation separate from the county. The town and the county do share some services, such as schools and the county landfill.
As of the census of 2000, there were 6,670 people, 2,683 households, and 1,591 families residing in the town. The population density was 1,574.8 people per square mile (607.4/km²). There were 2,856 housing units at an average density of 674.3/sq mi (260.1/km²). The racial makeup of the town was 80.04% White, 16.49% African American, 0.24% Native American, 1.00% Asian, 0.01% Pacific Islander, 0.63% from other races, and 1.57% from two or more races. Hispanic or Latino of any race were 3.25% of the population.
There were 2,683 households out of which 28.7% had children under the age of 18 living with them, 41.6% were married couples living together, 14.5% had a female householder with no husband present, and 40.7% were non-families. 33.7% of all households were made up of individuals and 13.2% had someone living alone who was 65 years of age or older. The average household size was 2.33 and the average family size was 3.01.
The population is fairly well distributed, with 23.9% under the age of 18, 6.7% from 18 to 24, 31.0% from 25 to 44, 21.0% from 45 to 64, and 17.5% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 84.8 males. For every 100 females age 18 and over, there were 77.8 males.
The median income for a household in the town was $50,760, and the median income for a family was $59,744. Males had a median income of $40,405 versus $31,689 for females. The per capita income for the town was $23,552. About 6.7% of families and 9.3% of the population were below the poverty line, including 9.3% of those under age 18 and 10.2% of those age 65 or over.