| Niagara Falls to Noventa Vicentina | 4,233.97 mi (6,813.92 km) |
| Niagara Falls to Novi di Modena | 4,223.16 mi (6,796.52 km) |
| Niagara Falls to Novi Ligure | 4,141.28 mi (6,664.74 km) |
| Niagara Falls to Nuoro | 4,334.72 mi (6,976.05 km) |
| Niagara Falls to Occhiobello | 4,249.79 mi (6,839.37 km) |
| Niagara Falls to Oderzo | 4,253.48 mi (6,845.32 km) |
| Niagara Falls to Oggiono | 4,126.52 mi (6,640.99 km) |
| Niagara Falls to Olbia | 4,318.30 mi (6,949.63 km) |
| Niagara Falls to Oleggio | 4,103.98 mi (6,604.72 km) |
| Niagara Falls to Olgiate Comasco | 4,110.89 mi (6,615.84 km) |
| Niagara Falls to Olgiate Olona | 4,112.99 mi (6,619.22 km) |
| Niagara Falls to Omegna | 4,084.56 mi (6,573.46 km) |
| Niagara Falls to Opera | 4,135.87 mi (6,656.04 km) |
| Niagara Falls to Oppeano | 4,219.15 mi (6,790.07 km) |
| Niagara Falls to Orbassano | 4,080.41 mi (6,566.78 km) |
