| Sierre to Mangualde | 860.19 mi (1,384.35 km) |
| Sierre to Marco de Canavezes | 857.03 mi (1,379.26 km) |
| Sierre to Marinha Grande | 944.28 mi (1,519.67 km) |
| Sierre to Massama | 998.97 mi (1,607.69 km) |
| Sierre to Matosinhos | 881.97 mi (1,419.39 km) |
| Sierre to Mealhada | 898.94 mi (1,446.71 km) |
| Sierre to Melgaco | 832.43 mi (1,339.67 km) |
| Sierre to Melres | 872.33 mi (1,403.88 km) |
| Sierre to Mira | 909.74 mi (1,464.08 km) |
| Sierre to Miranda do Corvo | 904.41 mi (1,455.51 km) |
| Sierre to Mirandela | 803.04 mi (1,292.37 km) |
| Sierre to Mogadouro | 787.42 mi (1,267.24 km) |
| Sierre to Moimenta da Beira | 840.01 mi (1,351.87 km) |
| Sierre to Moita | 990.91 mi (1,594.72 km) |
| Sierre to Moncao | 843.59 mi (1,357.63 km) |
