| Zip Code | City | Population ↓ |
|---|---|---|
| 51301 | Spencer | 12,326 |
| 51338 | Everly | 933 |
| 51357 | Royal | 744 |
| 51047 | Peterson | 690 |
| 51033 | Linn Grove | 460 |
| 51333 | Dickens | 394 |
| 51366 | Webb | 303 |
| 51343 | Greenville | 284 |
| 51340 | Fostoria | 93 |
| 51341 | Gillett Grove | 39 |
The data shown reflect ZCTAs from the US Census. As of 2024, there are 10 ZCTAs in Clay County, Iowa (US Census).