Area code 636

Area code 636 is a telephone area code in North American Numbering Plan (NANP) for the east-central part of the U.S. state of Missouri, comprising mainly the western suburbs of St. Louis. It includes parts of Chesterfield and Fenton in St. Louis County, and all of Troy, St. Charles, Jefferson, and Warren counties, as well as the towns of High Hill and Jonesburg in Montgomery County. It was created in 1999 in an area code split from area code 314, which was one of the original North American area codes of 1947.