| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| Obraje Nuevo | city | La Libertad | El Salvador | 13.95 | -89.31 | 1256 | 26898 |
| Obrajito | city | Chalatenango | El Salvador | 14.12 | -89.30 | 1036 | 11243 |
| Obrajuello Lempa | city | San Vicente | El Salvador | 13.58 | -88.67 | 331 | 19136 |
| Obrajuelo | city | Usulutan | El Salvador | 13.32 | -88.40 | 150 | 50607 |
| Obrajuelo | city | Usulutan | El Salvador | 13.32 | -88.38 | 141 | 46468 |
| Obrajuelo | city | Chalatenango | El Salvador | 14.13 | -89.22 | 941 | 9896 |
| Ocelotlan | city | Usulutan | El Salvador | 13.35 | -88.45 | 301 | 54710 |
| Ochupse Abajo | city | Santa Ana | El Salvador | 13.92 | -89.59 | 3349 | 77076 |
| Ochupse Arriba | city | Santa Ana | El Salvador | 13.90 | -89.58 | 3526 | 73249 |
| Ocotal | city | Chalatenango | El Salvador | 14.20 | -88.98 | 2739 | 11316 |
| Ocote | city | La Union | El Salvador | 13.83 | -87.78 | 1732 | 11626 |
| Ocote Seco | city | Morazan | El Salvador | 13.87 | -88.05 | 2509 | 10171 |
| Ocotillo | city | Morazan | El Salvador | 13.75 | -88.07 | 2509 | 20102 |
| Ocotillo | city | La Union | El Salvador | 13.82 | -87.87 | 2683 | 19409 |
| Ojeo | city | San Miguel | El Salvador | 13.77 | -88.48 | 830 | 3729 |
| Ojo de Agua | city | San Miguel | El Salvador | 13.47 | -88.35 | 2791 | 33850 |
| Ojo de Agua | city | Morazan | El Salvador | 13.85 | -88.18 | 1669 | 18676 |
| Ojo de Agua | city | San Miguel | El Salvador | 13.45 | -88.18 | 351 | 71063 |
| Ojo de Agua | city | Santa Ana | El Salvador | 14.15 | -89.53 | 1669 | 15513 |
| Ojo de Agua | city | La Libertad | El Salvador | 13.60 | -89.24 | 2509 | 111425 |
| Ojo de Agua | city | Chalatenango | El Salvador | 14.13 | -88.87 | 2509 | 8575 |
| Ojo de Agua | city | Cuscatlan | El Salvador | 13.75 | -88.93 | 2509 | 92146 |
| Ojo de Agua | city | Sonsonate | El Salvador | 13.87 | -89.72 | 3592 | 42083 |
| Ojo de Agua | city | Santa Ana | El Salvador | 14.15 | -89.63 | 2877 | 26359 |
| Ojo de Agua | city | Usulutan | El Salvador | 13.35 | -88.47 | 324 | 48143 |
| Ojo de Agua | city | Santa Ana | El Salvador | 13.90 | -89.70 | 6118 | 46420 |
| Ojo de Agua Arriba | city | Usulutan | El Salvador | 13.23 | -88.20 | 1053 | 10006 |
| Ojo de Agua Escondido | city | Chalatenango | El Salvador | 14.13 | -89.07 | 1049 | 19749 |
| Ojo de Agua de León | city | Usulutan | El Salvador | 13.22 | -88.19 | 1669 | 9580 |
| Ojos de Agua | city | Chalatenango | El Salvador | 14.22 | -89.22 | 1669 | 9025 |
| Ojos de Agua | city | La Libertad | El Salvador | 13.60 | -89.24 | 2509 | 111425 |
| Ojos de Agua | city | Chalatenango | El Salvador | 14.13 | -89.07 | 1049 | 19749 |
| Ojos de Agua | city | Morazan | El Salvador | 13.85 | -88.18 | 1669 | 18676 |
| Ojos de Agua | city | Chalatenango | El Salvador | 14.13 | -88.87 | 2509 | 8575 |
| Ojushte | city | Usulutan | El Salvador | 13.62 | -88.48 | 892 | 16632 |
| Ojushte | city | La Union | El Salvador | 13.40 | -87.98 | 967 | 15380 |
| Ojushtillo | city | La Union | El Salvador | 13.40 | -87.98 | 967 | 15380 |
| Olocuilta | city | La Paz | El Salvador | 13.57 | -89.12 | 1669 | 44546 |
| Olomega | city | La Union | El Salvador | 13.31 | -88.03 | 278 | 22549 |
| Olomeguita | city | San Miguel | El Salvador | 13.30 | -88.05 | 167 | 21284 |
| Olosingo | city | Chalatenango | El Salvador | 14.07 | -88.95 | 1952 | 29854 |
| Omoa | city | Santa Ana | El Salvador | 14.00 | -89.63 | 2509 | 53788 |
| Opico | city | La Libertad | El Salvador | 13.88 | -89.36 | 1669 | 31772 |
| Oratorio | city | Cabanas | El Salvador | 13.83 | -88.88 | 2509 | 34231 |
| Oratorio de Concepción | city | Cuscatlan | El Salvador | 13.82 | -89.06 | 1938 | 54973 |
| Oratorio de La Inmaculada Concepcion | city | Cuscatlan | El Salvador | 13.82 | -89.06 | 1938 | 54973 |
| Oromontique | city | San Miguel | El Salvador | 13.48 | -88.38 | 1942 | 34307 |
| Osicala | city | Morazan | El Salvador | 13.80 | -88.15 | 1696 | 24965 |
| Ostucal | city | San Miguel | El Salvador | 13.80 | -88.33 | 1669 | 25441 |
| Ostúa | city | Santa Ana | El Salvador | 14.33 | -89.55 | 1669 | 7510 |
| Ozatlán | city | Usulutan | El Salvador | 13.38 | -88.50 | 830 | 35105 |