| Clay to Mangualde | 4,221.80 mi (6,794.33 km) |
| Clay to Marco de Canavezes | 4,188.53 mi (6,740.79 km) |
| Clay to Marinha Grande | 4,185.35 mi (6,735.66 km) |
| Clay to Massama | 4,193.18 mi (6,748.26 km) |
| Clay to Matosinhos | 4,161.75 mi (6,697.69 km) |
| Clay to Mealhada | 4,193.51 mi (6,748.81 km) |
| Clay to Melgaco | 4,160.39 mi (6,695.50 km) |
| Clay to Melres | 4,179.20 mi (6,725.77 km) |
| Clay to Mira | 4,178.36 mi (6,724.42 km) |
| Clay to Miranda do Corvo | 4,206.29 mi (6,769.38 km) |
| Clay to Mirandela | 4,228.04 mi (6,804.38 km) |
| Clay to Mogadouro | 4,254.30 mi (6,846.64 km) |
| Clay to Moimenta da Beira | 4,219.65 mi (6,790.86 km) |
| Clay to Moita | 4,210.50 mi (6,776.15 km) |
| Clay to Moncao | 4,151.15 mi (6,680.63 km) |
