3420 is the Postal Code/ZIP Code for the of San Dionisio in the El Salvador Department of Usulután and the Municipality of San Dionisio.
| Postal Code | 3420 |
| Postal Code Name | San Dionisio |
| Department | Usulután Department |
| Municipality | San Dionisio Municipality |
| Timezone | Central Standard Time (CST) |
| Adjacent Postal Codes | 3401 |