Geographic Regions and Area Codes

Area code 636 is located in the east-central part of Missouri, primarily covering the western suburbs of St. Louis. It includes parts of St. Louis County, as well as all of St. Charles, Jefferson, Warren, and Franklin counties. Additionally, it covers parts of Lincoln and Montgomery counties. The major cities within this area code include O'Fallon, St. Charles, St. Peters, Chesterfield, and Wentzville. This region is known for its diverse range of industries and thriving economic environment.

Key regions within Area Code 636:

  • St. Charles
  • Chesterfield
  • Union
  • Troy
  • Wentzville