La Union has 576 barangays across 20 municipalities. 323 barangays (56%) are connectivity dead zones.
| Municipality | Barangays | Dead zones |
|---|---|---|
| Agoo | 49 | 24 (49%) |
| Aringay | 24 | 14 (58%) |
| Bacnotan | 47 | 31 (66%) |
| Bagulin | 10 | 10 (100%) |
| Balaoan | 36 | 21 (58%) |
| Bangar | 33 | 21 (64%) |
| Bauang | 39 | 17 (44%) |
| Burgos | 12 | 7 (58%) |
| Caba | 17 | 8 (47%) |
| City of San Fernando (Capital) | 59 | 16 (27%) |
| Luna | 40 | 31 (78%) |
| Naguilian | 37 | 27 (73%) |
| Pugo | 14 | 1 (7%) |
| Rosario | 33 | 7 (21%) |
| San Gabriel | 15 | 15 (100%) |
| San Juan | 41 | 24 (59%) |
| Santo Tomas | 24 | 14 (58%) |
| Santol | 11 | 10 (91%) |
| Sudipen | 17 | 15 (88%) |
| Tubao | 18 | 10 (56%) |