| Locality | Postal Code |
|---|---|
| Postal/ZIP Codes in Pueblo Italiano, Unión | X2653 |
| Postal/ZIP Codes in Pueblo Viejo, Unión | X2555 XAA |
| Postal/ZIP Codes in San Antonio de Litín, Unión | X2560 |
| Postal/ZIP Codes in San Carlos, Unión | X2572 XAA |
| Postal/ZIP Codes in San Eusebio, Unión | X2561 XAA |
| Postal/ZIP Codes in San José, Unión | X2563 XAA |
| Postal/ZIP Codes in San Marcos Sud, Unión | X2566 |
| Postal/ZIP Codes in San Meliton, Unión | X2664 XAA |
| Postal/ZIP Codes in San Pedro, Unión | X2559 XAA |
| Postal/ZIP Codes in San Vicente, Unión | X2550 XAA |
| Postal/ZIP Codes in Santa Cecilia, Unión | X2561 XAB |
| Postal/ZIP Codes in Santa María, Unión | X2651 XAA |
| Postal/ZIP Codes in Santa Rosa, Unión | X5913 XAE |
| Postal/ZIP Codes in Viamonte, Unión | X2651 |
| Postal/ZIP Codes in Villa los Patos, Unión | X2550 XAF |
| Postal/ZIP Codes in Wenceslao Escalante, Unión | X2655 |