| South Portland to Mangualde | 3,134.46 mi (5,044.42 km) |
| South Portland to Marco de Canavezes | 3,099.05 mi (4,987.43 km) |
| South Portland to Marinha Grande | 3,104.31 mi (4,995.91 km) |
| South Portland to Massama | 3,118.35 mi (5,018.50 km) |
| South Portland to Matosinhos | 3,073.08 mi (4,945.64 km) |
| South Portland to Mealhada | 3,108.36 mi (5,002.42 km) |
| South Portland to Melgaco | 3,066.90 mi (4,935.70 km) |
| South Portland to Melres | 3,090.63 mi (4,973.89 km) |
| South Portland to Mira | 3,093.42 mi (4,978.37 km) |
| South Portland to Miranda do Corvo | 3,122.38 mi (5,024.98 km) |
| South Portland to Mirandela | 3,135.83 mi (5,046.63 km) |
| South Portland to Mogadouro | 3,162.10 mi (5,088.92 km) |
| South Portland to Moimenta da Beira | 3,130.31 mi (5,037.75 km) |
| South Portland to Moita | 3,135.71 mi (5,046.43 km) |
| South Portland to Moncao | 3,058.12 mi (4,921.57 km) |
