Zip Code | City | Population |
|---|---|---|
| 63376 | Saint Peters | 74,967 |
| 63366 | O'Fallon | 52,746 |
| 63301 | Saint Charles | 51,401 |
| 63385 | Wentzville | 48,535 |
| 63303 | Saint Charles | 47,285 |
| 63368 | O'Fallon | 46,124 |
| 63304 | Saint Charles | 42,738 |
| 63367 | Lake Saint Louis | 27,371 |
| 63348 | Foristell | 10,555 |
| 63341 | Defiance | 3,628 |
| 63332 | Augusta | 1,742 |
| 63373 | Portage Des Sioux | 687 |
| 63386 | West Alton | 522 |
| 63365 | New Melle | 66 |