| Keystone to Mangualde | 4,227.54 mi (6,803.56 km) |
| Keystone to Marco de Canavezes | 4,198.47 mi (6,756.79 km) |
| Keystone to Marinha Grande | 4,181.31 mi (6,729.17 km) |
| Keystone to Massama | 4,179.85 mi (6,726.82 km) |
| Keystone to Matosinhos | 4,170.61 mi (6,711.95 km) |
| Keystone to Mealhada | 4,195.94 mi (6,752.72 km) |
| Keystone to Melgaco | 4,178.19 mi (6,724.15 km) |
| Keystone to Melres | 4,187.63 mi (6,739.35 km) |
| Keystone to Mira | 4,180.64 mi (6,728.09 km) |
| Keystone to Miranda do Corvo | 4,206.52 mi (6,769.74 km) |
| Keystone to Mirandela | 4,242.51 mi (6,827.66 km) |
| Keystone to Mogadouro | 4,268.41 mi (6,869.35 km) |
| Keystone to Moimenta da Beira | 4,228.91 mi (6,805.77 km) |
| Keystone to Moita | 4,196.89 mi (6,754.24 km) |
| Keystone to Moncao | 4,168.17 mi (6,708.03 km) |
