| Locality | Post Code |
|---|---|
| Bath, Mason | 62617 |
| Biggs, Mason | 62633 |
| Bishop, Mason | 61532 |
| Easton, Mason | 62633 |
| Eckard, Mason | 62644 |
| Enion, Mason | 62644 |
| Forest City, Mason | 61532 |
| Goofy Ridge, Mason | 61567 |
| Havana, Mason | 62644 |
| Kilbourne, Mason | 62655 |
| Luther, Mason | 62664 |
| Lynchburg, Mason | 62617 |
| Manito, Mason | 61546 |
| Mason City, Mason | 62664 |
| Parkland, Mason | 61546 |
| Poplar City, Mason | 62633 |
| San Jose, Mason | 62682 |
| Snicarte, Mason | 62617 |
| Spring Lake, Mason | 61546 |
| Talbott, Mason | 61546 |
| Teheran, Mason | 62664 |
| Topeka, Mason | 61567 |