| Niagara Falls to Octeville | 3,551.35 mi (5,715.35 km) |
| Niagara Falls to Oignies | 3,712.63 mi (5,974.90 km) |
| Niagara Falls to Oissel | 3,670.86 mi (5,907.67 km) |
| Niagara Falls to Olivet | 3,749.70 mi (6,034.55 km) |
| Niagara Falls to Ollioules | 4,077.32 mi (6,561.81 km) |
| Niagara Falls to Olonne-sur-Mer | 3,637.24 mi (5,853.57 km) |
| Niagara Falls to Oloron-Sainte-Marie | 3,795.22 mi (6,107.82 km) |
| Niagara Falls to Onet Village | 3,894.51 mi (6,267.61 km) |
| Niagara Falls to Onnaing | 3,738.96 mi (6,017.27 km) |
| Niagara Falls to Orange | 3,997.06 mi (6,432.65 km) |
| Niagara Falls to Orchies | 3,722.34 mi (5,990.53 km) |
| Niagara Falls to Orleans | 3,748.82 mi (6,033.14 km) |
| Niagara Falls to Orly | 3,742.04 mi (6,022.23 km) |
| Niagara Falls to Ormesson-sur-Marne | 3,746.62 mi (6,029.60 km) |
| Niagara Falls to Orsay | 3,735.14 mi (6,011.12 km) |
