11 ZIP Codes
| Zip Code | City | Population ↓ |
|---|---|---|
| 51031 | Le Mars | 12,808 |
| 51108 | Sioux City | 5,960 |
| 51109 | Sioux City | 3,606 |
| 51050 | Remsen | 2,962 |
| 51001 | Akron | 2,342 |
| 51028 | Kingsley | 2,191 |
| 51024 | Hinton | 2,081 |
| 51038 | Merrill | 1,449 |
| 51062 | Westfield | 503 |
| 51008 | Brunsville | 210 |
| 51045 | Oyens | 66 |
The data shown reflect ZCTAs from the US Census. As of 2025, there are 11 ZCTAs in Plymouth County, Iowa (US Census).