43 zips
| Zip Code | City | Population ↓ |
|---|---|---|
| 63021 | Ballwin | 56,297 |
| 63129 | Saint Louis | 51,356 |
| 63031 | Florissant | 50,258 |
| 63123 | Saint Louis | 49,826 |
| 63017 | Chesterfield | 43,074 |
| 63033 | Florissant | 42,258 |
| 63122 | Saint Louis | 41,724 |
| 63136 | Saint Louis | 41,314 |
| 63011 | Ballwin | 36,274 |
| 63119 | Saint Louis | 34,574 |
| 63114 | Saint Louis | 33,703 |
| 63125 | Saint Louis | 32,701 |
| 63146 | Saint Louis | 30,917 |
| 63128 | Saint Louis | 30,106 |
| 63130 | Saint Louis | 29,074 |
| 63121 | Saint Louis | 24,571 |
| 63043 | Maryland Heights | 21,651 |
| 63141 | Saint Louis | 20,640 |
| 63137 | Saint Louis | 19,690 |
| 63005 | Chesterfield | 19,679 |
| 63034 | Florissant | 19,557 |
| 63135 | Saint Louis | 19,446 |
| 63105 | Saint Louis | 18,860 |
| 63138 | Saint Louis | 18,736 |
| 63025 | Eureka | 18,483 |
| 63131 | Saint Louis | 17,993 |
| 63042 | Hazelwood | 17,953 |
| 63074 | Saint Ann | 16,237 |
| 63126 | Saint Louis | 15,373 |
| 63132 | Saint Louis | 13,953 |
| 63134 | Saint Louis | 13,460 |
| 63124 | Saint Louis | 11,009 |
| 63044 | Bridgeton | 10,510 |
| 63144 | Saint Louis | 9,580 |
| 63117 | Saint Louis | 9,188 |
| 63143 | Saint Louis | 8,968 |
| 63040 | Wildwood | 8,826 |
| 63088 | Valley Park | 8,423 |
| 63038 | Wildwood | 7,132 |
| 63133 | Saint Louis | 6,375 |
| 63127 | Saint Louis | 5,161 |
| 63140 | Saint Louis | 350 |
| 63045 | Earth City | 0 |
The data shown reflect ZCTAs from the US Census. As of 2024, there are 43 ZCTAs in St. Louis County, Missouri (US Census).