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