O’Fallon is located along Interstate 70 and Interstate 64 between Lake St. Louis and St. Peters in Saint Charles County, Missouri. It is part of the St. Louis Metropolitan Statistical Area. As of the 2010 census O’Fallon had a population of 79,329, making the city the largest municipality in St. Charles County and seventh largest in the state of Missouri. In 2006 Money Magazine named O’Fallon as one of its “Best 100 Places to Live” (39 out of 100). Money Magazine also ranked O’Fallon 26 out of 100 in 2010.
The median income for a household in the city is $60,179, and the median income for a family is $64,627. Males have a median income of $45,295 versus $29,129 for females. The per capita income for the city is $21,774. 3.3% of the population and 2.6% of families are below the poverty line. Out of the total population, 3.3% of those under the age of 18 and 6.7% of those 65 and older are living below the poverty line.