27 ZIP Codes
| Zip Code | City | Population ↓ |
|---|---|---|
| 62269 | O'Fallon | 35,923 |
| 62221 | Belleville | 29,875 |
| 62226 | Belleville | 28,255 |
| 62220 | Belleville | 19,152 |
| 62208 | Fairview Heights | 16,821 |
| 62223 | Belleville | 16,269 |
| 62206 | East Saint Louis | 12,959 |
| 62258 | Mascoutah | 10,437 |
| 62232 | Caseyville | 7,063 |
| 62207 | East Saint Louis | 6,984 |
| 62254 | Lebanon | 6,710 |
| 62260 | Millstadt | 6,668 |
| 62205 | East Saint Louis | 6,459 |
| 62243 | Freeburg | 6,418 |
| 62203 | East Saint Louis | 5,465 |
| 62225 | Scott Air Force Base | 5,242 |
| 62201 | East Saint Louis | 4,921 |
| 62285 | Smithton | 4,239 |
| 62239 | Dupo | 4,232 |
| 62204 | East Saint Louis | 4,055 |
| 62264 | New Athens | 3,097 |
| 62257 | Marissa | 2,046 |
| 62240 | East Carondelet | 1,796 |
| 62255 | Lenzburg | 1,092 |
| 62059 | Lovejoy | 729 |
| 62282 | Saint Libory | 563 |
| 62289 | Summerfield | 273 |
The data shown reflect ZCTAs from the US Census. As of 2025, there are 27 ZCTAs in St. Clair County, Illinois (US Census).