High Quality Content by WIKIPEDIA articles! O`Fallon (Template:Pron-en) is a suburban city along Interstate 70 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 population of 79,329, it is the seventh largest city in the state and the largest in St. Charles County. 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 68 out of 100 in 2008 and 26 out of 100 in 2010