O'Fallon is a city located in Missouri. With a 2020 population of 89,291, it is the 7th largest city in Missouri and the 382nd largest city in the United States . O'Fallon is currently growing at a rate of 0.35% annually and its population has increased by 12.56% since the most recent census, which recorded a population of 79,329 in 2010. O'Fallon reached it's highest population of in . Spanning over 30 miles, O'Fallon has a population density of 2,998 people per square mile.
The average household income in O'Fallon is $108,521 with a poverty rate of 4.45%. The median rental costs in recent years comes to $1,103 per month, and the median house value is $226,300. The median age in O'Fallon is 37 years, 35 years for males, and 38.7 years for females.