| Southborough to Mangualde | 824.05 mi (1,326.17 km) |
| Southborough to Marco de Canavezes | 797.10 mi (1,282.81 km) |
| Southborough to Marinha Grande | 904.06 mi (1,454.94 km) |
| Southborough to Massama | 973.80 mi (1,567.18 km) |
| Southborough to Matosinhos | 810.54 mi (1,304.44 km) |
| Southborough to Mealhada | 853.51 mi (1,373.59 km) |
| Southborough to Melgaco | 743.35 mi (1,196.31 km) |
| Southborough to Melres | 810.26 mi (1,303.98 km) |
| Southborough to Mira | 857.14 mi (1,379.43 km) |
| Southborough to Miranda do Corvo | 868.42 mi (1,397.58 km) |
| Southborough to Mirandela | 756.11 mi (1,216.83 km) |
| Southborough to Mogadouro | 755.66 mi (1,216.12 km) |
| Southborough to Moimenta da Beira | 797.29 mi (1,283.11 km) |
| Southborough to Moita | 973.89 mi (1,567.33 km) |
| Southborough to Moncao | 751.44 mi (1,209.32 km) |
