Warrenton is a city in Warren County, Missouri, United States. The population was estimated at 7,398 in 2008. It is the county seat of Warren County. Warrenton is located in the St. Louis Metropolitan Statistical Area. Warrenton's slogan is "A City for All Seasons."
Warrenton is located at 38°48′57″N 91°8′25″W / 38.81583°N 91.14028°W / 38.81583; -91.14028 (38.815951, -91.140164). According to the United States Census Bureau, the city has a total area of 7.3 square miles (19.0 km²), of which, 7.3 square miles (19.0 km²) of it is land and 0.14% is water.
As of the census of 2000, there were 5,281 people, 1,985 households, and 1,363 families residing in the city. The population density was 720.6 people per square mile (278.2/km²). There were 2,110 housing units at an average density of 287.9 per square mile (111.1/km²). The racial makeup of the city was 95.64% White, 1.70% African American, 0.42% Native American, 0.38% Asian, 0.04% Pacific Islander, 0.57% from other races, and 1.25% from two or more races. Hispanic or Latino of any race were 1.29% of the population.