14 zips
| Zip Code | City | Population ↓ |
|---|---|---|
| 63376 | Saint Peters | 74,876 |
| 63366 | O'Fallon | 54,449 |
| 63301 | Saint Charles | 51,625 |
| 63385 | Wentzville | 50,420 |
| 63303 | Saint Charles | 46,627 |
| 63368 | O'Fallon | 45,862 |
| 63304 | Saint Charles | 43,389 |
| 63367 | Lake Saint Louis | 27,893 |
| 63348 | Foristell | 10,207 |
| 63341 | Defiance | 3,554 |
| 63332 | Augusta | 1,676 |
| 63373 | Portage Des Sioux | 717 |
| 63386 | West Alton | 537 |
| 63365 | New Melle | 56 |
The data shown reflect ZCTAs from the US Census. As of 2024, there are 14 ZCTAs in St. Charles County, Missouri (US Census).