| Locality | Post Code |
|---|---|
| Big Bar, Trinity | 96010 |
| Burnt Ranch, Trinity | 95527 |
| Douglas City, Trinity | 96024 |
| Hayfork, Trinity | 96041 |
| Helena, Trinity | 96048 |
| Hyampom, Trinity | 96046 |
| Junction City, Trinity | 96048 |
| Lewiston, Trinity | 96052 |
| Mad River, Trinity | 95552 |
| Peanut, Trinity | 96041 |
| Salyer, Trinity | 95563 |
| Trinity Center, Trinity | 96091 |
| Weaverville, Trinity | 96093 |
| Zenia, Trinity | 95595 |