St. Charles, Missouri From Wikipedia, the free encyclopedia St. Charles, MissouriCountryStateCountyGovernment • MayorArea[1] • Total • Land • WaterPopulation (2020) • Total • DensityTime zone • Summer (DST)ZIP CodesArea codesFIPS codeWaterwaysWebsite City City of St. Charles Historic Main Street Flag Location in the state of Missouri Coordinates: 38.789°N 90.514°WCoordinates: 38.789°N 90.514°W U..