| Zip Code | City | Population ↓ |
|---|---|---|
| 51250 | Sioux Center | 9,667 |
| 51041 | Orange City | 7,016 |
| 51201 | Sheldon | 6,278 |
| 51247 | Rock Valley | 4,887 |
| 51023 | Hawarden | 3,469 |
| 51239 | Hull | 3,115 |
| 51003 | Alton | 1,761 |
| 51027 | Ireton | 1,421 |
| 51238 | Hospers | 1,401 |
| 51234 | Boyden | 1,179 |
| 51036 | Maurice | 676 |
| 51244 | Matlock | 147 |
| 51011 | Chatsworth | 77 |
The data shown reflect ZCTAs from the US Census. As of 2024, there are 13 ZCTAs in Sioux County, Iowa (US Census).