Some Ideas on O'fallon Zip Code You Should Know Table of ContentsAll About O'fallon IlThe Basic Principles Of O'fallon Weather Not known Details About O'fallon Zip Code The Of O'fallon WeatherO'Fallon is a city in St. Clair Region, Illinois, which was started in 1854. O'Fallon's name comes from Colonel John O'Fallon, that was an affluent gent from