| Zip Code | City | Population ↓ |
|---|---|---|
| 50158 | Marshalltown | 31,047 |
| 50247 | State Center | 2,411 |
| 50162 | Melbourne | 1,302 |
| 50106 | Gilman | 1,182 |
| 50005 | Albion | 859 |
| 50142 | Le Grand | 790 |
| 50120 | Haverhill | 537 |
| 50141 | Laurel | 499 |
| 50234 | Rhodes | 482 |
| 50148 | Liscomb | 376 |
| 50051 | Clemons | 277 |
| 50239 | Saint Anthony | 139 |
| 50078 | Ferguson | 102 |
The data shown reflect ZCTAs from the US Census. As of 2024, there are 13 ZCTAs in Marshall County, Iowa (US Census).