O'Fallon is a city located in Missouri. With a 2020 population of 90,684, it is the 7th largest city in Missouri and the 373rd largest city in the United States. O'Fallon is currently growing at a rate of 1.23% annually and its population has increased by 14.31% since the most recent census, which recorded a population of 79,329 in 2010. Spanning over 30 miles, O'Fallon has a population density of 3,045 people per square mile.
The average household income in O'Fallon is $104,195 with a poverty rate of 4.76%. The median rental costs in recent years comes to $1,090 per month, and the median house value is $217,000. The median age in O'Fallon is 36.5 years, 35.1 years for males, and 38.1 years for females. For every 100 females there are 97.3 males.