| Killarney to Olympia Heights (Florida) | 4,034.17 mi (6,492.36 km) |
| Killarney to Omaha (Nebraska) | 3,922.59 mi (6,312.80 km) |
| Killarney to On Top of the World Designated Place (Florida) | 3,947.67 mi (6,353.16 km) |
| Killarney to Onalaska (Wisconsin) | 3,617.74 mi (5,822.19 km) |
| Killarney to Oneida (New York) | 3,035.28 mi (4,884.81 km) |
| Killarney to Oneonta (New York) | 3,036.13 mi (4,886.18 km) |
| Killarney to Ontario (California) | 5,081.85 mi (8,178.45 km) |
| Killarney to Ontario (Oregon) | 4,522.61 mi (7,278.44 km) |
| Killarney to Opa-locka (Florida) | 4,021.74 mi (6,472.36 km) |
| Killarney to Opelika (Alabama) | 3,903.59 mi (6,282.23 km) |
| Killarney to Opelousas (Louisiana) | 4,285.83 mi (6,897.38 km) |
| Killarney to Orange (California) | 5,102.28 mi (8,211.33 km) |
| Killarney to Orange (Texas) | 4,374.88 mi (7,040.69 km) |
| Killarney to Orange City (Florida) | 3,913.94 mi (6,298.87 km) |
| Killarney to Orangeburg (South Carolina) | 3,675.45 mi (5,915.06 km) |
