| Locality | Post Code |
|---|---|
| Baltimore, Northumberland | K0K |
| Bewdley, Northumberland | K0L 0A4, K0L 1E0 |
| Brighton, Northumberland | K0K |
| Campbellcroft, Northumberland | L0A |
| Campbellford, Northumberland | K0L |
| Castleton, Northumberland | K0K |
| Cobourg, Northumberland | K9A |
| Codrington, Northumberland | K0K 1R0 |
| Colborne, Northumberland | K0K |
| Gores Landing, Northumberland | K0K 2E0 |
| Grafton, Northumberland | K0K |
| Hamilton Township, Northumberland | K0L 1E0 |
| Harwood, Northumberland | K0K 0C2, K0K 2H0 |
| Hastings, Northumberland | K0L |
| Port Hope, Northumberland | L1A |
| Roseneath, Northumberland | K0K |
| Trent River, Northumberland | K0L 2Z0 |
| Warkworth, Northumberland | K0K |