14 ZIP Codes
| Zip Code | City | Population ↓ |
|---|---|---|
| 63376 | Saint Peters | 74,962 |
| 63366 | O'Fallon | 54,769 |
| 63301 | Saint Charles | 52,667 |
| 63385 | Wentzville | 51,330 |
| 63368 | O'Fallon | 46,966 |
| 63303 | Saint Charles | 46,089 |
| 63304 | Saint Charles | 43,195 |
| 63367 | Lake Saint Louis | 29,725 |
| 63348 | Foristell | 10,394 |
| 63341 | Defiance | 3,515 |
| 63332 | Augusta | 1,651 |
| 63373 | Portage Des Sioux | 690 |
| 63386 | West Alton | 482 |
| 63365 | New Melle | 51 |
The data shown reflect ZCTAs from the US Census. As of 2025, there are 14 ZCTAs in St. Charles County, Missouri (US Census).