43 ZIP Codes
| Zip Code | City | Population ↓ |
|---|---|---|
| 63021 | Ballwin | 55,666 |
| 63129 | Saint Louis | 51,553 |
| 63031 | Florissant | 50,196 |
| 63123 | Saint Louis | 49,077 |
| 63017 | Chesterfield | 43,243 |
| 63033 | Florissant | 43,056 |
| 63122 | Saint Louis | 41,634 |
| 63136 | Saint Louis | 40,929 |
| 63011 | Ballwin | 35,920 |
| 63119 | Saint Louis | 34,181 |
| 63114 | Saint Louis | 33,969 |
| 63125 | Saint Louis | 33,294 |
| 63146 | Saint Louis | 30,678 |
| 63128 | Saint Louis | 30,540 |
| 63130 | Saint Louis | 28,910 |
| 63121 | Saint Louis | 25,008 |
| 63043 | Maryland Heights | 21,924 |
| 63141 | Saint Louis | 20,932 |
| 63005 | Chesterfield | 19,779 |
| 63137 | Saint Louis | 19,684 |
| 63025 | Eureka | 19,508 |
| 63034 | Florissant | 18,908 |
| 63105 | Saint Louis | 18,875 |
| 63135 | Saint Louis | 18,381 |
| 63138 | Saint Louis | 18,233 |
| 63131 | Saint Louis | 17,935 |
| 63042 | Hazelwood | 17,813 |
| 63074 | Saint Ann | 15,793 |
| 63126 | Saint Louis | 15,452 |
| 63132 | Saint Louis | 14,283 |
| 63134 | Saint Louis | 13,059 |
| 63124 | Saint Louis | 10,839 |
| 63044 | Bridgeton | 10,324 |
| 63144 | Saint Louis | 9,505 |
| 63117 | Saint Louis | 9,261 |
| 63143 | Saint Louis | 8,975 |
| 63040 | Wildwood | 8,526 |
| 63088 | Valley Park | 8,226 |
| 63038 | Wildwood | 7,107 |
| 63133 | Saint Louis | 6,569 |
| 63127 | Saint Louis | 5,268 |
| 63140 | Saint Louis | 316 |
| 63045 | Earth City | 0 |
The data shown reflect ZCTAs from the US Census. As of 2025, there are 43 ZCTAs in St. Louis County, Missouri (US Census).