<Tr> <Th> Area code (s) </Th> <Td> 636, 314 </Td> </Tr> <Tr> <Th> Website </Th> <Td> www.stcharlescitymo.gov </Td> </Tr> <P> St. Charles is a city in, and the county seat of, St. Charles County, Missouri, United States . The population was 65,794 at the 2010 census, making St. Charles the ninth - largest city in Missouri . It lies to the northwest, and is a suburb of St. Louis, Missouri on the Missouri River . </P> <P> Founded in about 1769 as Les Petites Côtes, or "The Little Shores" in French, by Louis Blanchette, a French - Canadian fur trader, when the area was nominally ruled by Spain following the Seven Years' War, it is the third - oldest city in Missouri . For a time, it played a significant role in the United States' westward expansion as a river port and starting point of the Boone's Lick Road to the Boonslick . </P>

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