O’Fallon is a city in St. Clair County, Illinois, United States. The 2010 census listed the population at 28,281. The city is the third largest city in the Metro-East region and Southern Illinois. It sits 5 miles (8.0 km) from Scott Air Force Base and 18 miles (29 km) from Downtown St Louis.
O’Fallon is located at 38°35′N 89°54′W / 38.583°N 89.900°W / 38.583; -89.900 (38.591549, −89.912000). O’Fallon is:
According to the 2010 census, the city has a total area of 14.48 square miles (37.5 km), of which 14.35 square miles (37.2 km) (or 99.10%) is land and 0.12 square miles (0.31 km) (or 0.83%) is water.
As of the census of 2010, there were 28,281 people, 8,310 households, and 6,016 families residing in the city. The population density was 1,970/sq mi (760/km). There were 8,310 housing units at an average density of 580/sq mi (220/km). The racial makeup of the city was 82.67% White, 11.99% African American, 0.23% Native American, 2.47% Asian, 0.07% Pacific Islander, 0.79% from other races, and 1.77% from two or more races. Hispanic or Latino of any race were 2.23% of the population.
There were 8,310 households out of which 39.6% had children under the age of 18 living with them, 59.0% were married couples living together, 10.5% had a female householder with no husband present, and 27.6% were non-families. 23.2% of all households were made up of individuals and 7.2% had someone living alone who was 65 years of age or older. The average household size was 2.62 and the average family size was 3.13.
In the city, the population was spread out with 28.3% under the age of 18, 8.0% from 18 to 24, 32.2% from 25 to 44, 22.7% from 45 to 64, and 8.9% who were 65 years of age or older. The median age was 35 years. For every 100 females, there were 93.2 males. For every 100 females age 18 and over, there were 90.1 males.
The median income for a household in the city was $55,927, and the median income for a family was $66,262. Males had a median income of $46,303 versus $30,158 for females. The per capita income for the city was $24,821. About 4.1% of families and 5.0% of the population were below the poverty line, including 5.0% of those under age 18 and 7.9% of those age 65 or over.