| Locality | Post Code |
|---|---|
| Ackley, Grundy | 50601 |
| Aplington, Grundy | 50604 |
| Beaman, Grundy | 50609 |
| Conrad, Grundy | 50621 |
| Dike, Grundy | 50624 |
| Dinsdale, Grundy | 50669 |
| Grundy Center, Grundy | 50638 |
| Holland, Grundy | 50642 |
| Morrison, Grundy | 50657 |
| Parkersburg, Grundy | 50665 |
| Reinbeck, Grundy | 50669 |
| Stout, Grundy | 50673 |
| Wellsburg, Grundy | 50680 |