| River Grove to Mangualde | 3,996.77 mi (6,432.19 km) |
| River Grove to Marco de Canavezes | 3,959.26 mi (6,371.82 km) |
| River Grove to Marinha Grande | 3,972.74 mi (6,393.51 km) |
| River Grove to Massama | 3,991.52 mi (6,423.74 km) |
| River Grove to Matosinhos | 3,934.36 mi (6,331.74 km) |
| River Grove to Mealhada | 3,973.04 mi (6,393.98 km) |
| River Grove to Melgaco | 3,922.47 mi (6,312.61 km) |
| River Grove to Melres | 3,951.91 mi (6,359.99 km) |
| River Grove to Mira | 3,958.39 mi (6,370.41 km) |
| River Grove to Miranda do Corvo | 3,988.15 mi (6,418.30 km) |
| River Grove to Mirandela | 3,992.58 mi (6,425.43 km) |
| River Grove to Mogadouro | 4,018.70 mi (6,467.47 km) |
| River Grove to Moimenta da Beira | 3,990.50 mi (6,422.09 km) |
| River Grove to Moita | 4,008.81 mi (6,451.56 km) |
| River Grove to Moncao | 3,914.36 mi (6,299.55 km) |
