Not known Facts About O'fallon LocationTable of Contents8 Easy Facts About O'fallon Zip Code ExplainedAll about O'fallon Zip CodeO'fallon Things To Know Before You Get ThisO'fallon Weather for BeginnersO'Fallon is a city in St. Clair Region, Illinois, which was established in 1854. O'Fallon's name comes from Colonel John O'Fallon, who was an afflue