The following are the zip codes in the municipalities and city of La Union.
| Region | Provinces | City/Municipality | Zip Code |
| Region 1 (Ilocos Region) | La Union | Tubao | 2509 |
| Region 1 (Ilocos Region) | La Union | Sudipen | 2520 |
| Region 1 (Ilocos Region) | La Union | Santo Tomas | 2505 |
| Region 1 (Ilocos Region) | La Union | Santol | 2516 |
| Region 1 (Ilocos Region) | La Union | San Juan | 2514 |
| Region 1 (Ilocos Region) | La Union | San Gabriel | 2513 |
| Region 1 (Ilocos Region) | La Union | San Fernando City | 2500 |
| Region 1 (Ilocos Region) | La Union | Rosario | 2506 |
| Region 1 (Ilocos Region) | La Union | Pugo | 2508 |
| Region 1 (Ilocos Region) | La Union | Naguilian | 2511 |
| Region 1 (Ilocos Region) | La Union | Luna | 2518 |
| Region 1 (Ilocos Region) | La Union | Caba | 2502 |
| Region 1 (Ilocos Region) | La Union | Burgos | 2510 |
| Region 1 (Ilocos Region) | La Union | Bauang | 2501 |
| Region 1 (Ilocos Region) | La Union | Bangar | 2519 |
| Region 1 (Ilocos Region) | La Union | Balaoan | 2517 |
| Region 1 (Ilocos Region) | La Union | Bagulin | 2512 |
| Region 1 (Ilocos Region) | La Union | Bacnotan | 2515 |
| Region 1 (Ilocos Region) | La Union | Aringay | 2503 |
| Region 1 (Ilocos Region) | La Union | Agoo | 2504 |
