| Round Rock to Mangualde | 4,879.96 mi (7,853.53 km) |
| Round Rock to Marco de Canavezes | 4,845.19 mi (7,797.59 km) |
| Round Rock to Marinha Grande | 4,847.28 mi (7,800.94 km) |
| Round Rock to Massama | 4,858.24 mi (7,818.59 km) |
| Round Rock to Matosinhos | 4,818.97 mi (7,755.38 km) |
| Round Rock to Mealhada | 4,853.06 mi (7,810.24 km) |
| Round Rock to Melgaco | 4,813.98 mi (7,747.35 km) |
| Round Rock to Melres | 4,836.50 mi (7,783.60 km) |
| Round Rock to Mira | 4,838.02 mi (7,786.04 km) |
| Round Rock to Miranda do Corvo | 4,866.60 mi (7,832.03 km) |
| Round Rock to Mirandela | 4,882.68 mi (7,857.92 km) |
| Round Rock to Mogadouro | 4,908.96 mi (7,900.22 km) |
| Round Rock to Moimenta da Beira | 4,876.43 mi (7,847.86 km) |
| Round Rock to Moita | 4,875.60 mi (7,846.53 km) |
| Round Rock to Moncao | 4,805.11 mi (7,733.08 km) |
