List of Missouri area codes
In 1947, when the American Telephone and Telegraph Company published the first configuration of a nationwide telephone numbering plan, the first version of the North American Numbering Plan, the U.S. state of Missouri was divided into two numbering plan areas. In 1950, the boundaries were redrawn in the creation of a third numbering plan area, 816. This configuration was stable for forty years into the 1990s, when rapid expansion of telecommunication service required additional area codes.
| Area code | Created | Parent NPA | Overlay | Numbering plan area |
| 314 | 1947 | – | 314/557 | St. Louis and many of its immediate suburbs |
| 557 | 2022 | 314 | 314/557 | St. Louis and many of its immediate suburbs |
| 573 | 1996 | 314 | 235/573 | Eastern and southeastern Missouri |
| 235 | 2024 | 573 | 235/573 | Eastern and southeastern Missouri |
| 636 | 1999 | 314 | – | St. Charles, Jefferson, and western St. Louis counties, which forms a ring around the immediate St. Louis area |
| 816 | 1947 | – | 816/975 | Kansas City and St. Joseph metropolitan areas |
| 975 | 2002 | 816 | 816/975 | Kansas City and St. Joseph metropolitan areas |
| 417 | 1950 | 816, 314 | – | Southwestern part of Missouri |
| 660 | 1997 | 816 | – | Northern and western Missouri |