| Sligo to Olympia Heights (Florida) | 4,071.26 mi (6,552.06 km) |
| Sligo to Omaha (Nebraska) | 3,894.11 mi (6,266.96 km) |
| Sligo to On Top of the World Designated Place (Florida) | 3,973.41 mi (6,394.59 km) |
| Sligo to Onalaska (Wisconsin) | 3,590.90 mi (5,779.00 km) |
| Sligo to Oneida (New York) | 3,037.15 mi (4,887.82 km) |
| Sligo to Oneonta (New York) | 3,041.02 mi (4,894.05 km) |
| Sligo to Ontario (California) | 5,029.43 mi (8,094.09 km) |
| Sligo to Ontario (Oregon) | 4,454.56 mi (7,168.93 km) |
| Sligo to Opa-locka (Florida) | 4,058.65 mi (6,531.76 km) |
| Sligo to Opelika (Alabama) | 3,915.02 mi (6,300.62 km) |
| Sligo to Opelousas (Louisiana) | 4,288.63 mi (6,901.88 km) |
| Sligo to Orange (California) | 5,049.85 mi (8,126.94 km) |
| Sligo to Orange (Texas) | 4,375.18 mi (7,041.16 km) |
| Sligo to Orange City (Florida) | 3,942.13 mi (6,344.24 km) |
| Sligo to Orangeburg (South Carolina) | 3,693.92 mi (5,944.79 km) |
