| Niagara Falls to Montalegre | 3,516.57 mi (5,659.38 km) |
| Niagara Falls to Montemor-o-Novo | 3,599.89 mi (5,793.47 km) |
| Niagara Falls to Montemor-o-Velho | 3,528.03 mi (5,677.82 km) |
| Niagara Falls to Montijo | 3,566.52 mi (5,739.77 km) |
| Niagara Falls to Mortagua | 3,540.39 mi (5,697.71 km) |
| Niagara Falls to Moura | 3,653.59 mi (5,879.88 km) |
| Niagara Falls to Murtosa | 3,512.18 mi (5,652.31 km) |
| Niagara Falls to Nazare | 3,528.47 mi (5,678.52 km) |
| Niagara Falls to Nelas | 3,555.51 mi (5,722.04 km) |
| Niagara Falls to Obidos | 3,532.08 mi (5,684.34 km) |
| Niagara Falls to Odemira | 3,616.31 mi (5,819.89 km) |
| Niagara Falls to Odivelas | 3,549.75 mi (5,712.77 km) |
| Niagara Falls to Oeiras | 3,546.82 mi (5,708.06 km) |
| Niagara Falls to Olhao | 3,673.27 mi (5,911.55 km) |
| Niagara Falls to Oliveira de Azemeis | 3,516.13 mi (5,658.66 km) |
