| Clayton to Mangualde | 951.52 mi (1,531.33 km) |
| Clayton to Marco de Canavezes | 918.49 mi (1,478.17 km) |
| Clayton to Marinha Grande | 1,025.15 mi (1,649.81 km) |
| Clayton to Massama | 1,096.14 mi (1,764.06 km) |
| Clayton to Matosinhos | 926.91 mi (1,491.72 km) |
| Clayton to Mealhada | 975.95 mi (1,570.64 km) |
| Clayton to Melgaco | 858.67 mi (1,381.89 km) |
| Clayton to Melres | 929.95 mi (1,496.60 km) |
| Clayton to Mira | 976.89 mi (1,572.16 km) |
| Clayton to Miranda do Corvo | 993.07 mi (1,598.20 km) |
| Clayton to Mirandela | 884.98 mi (1,424.24 km) |
| Clayton to Mogadouro | 889.45 mi (1,431.43 km) |
| Clayton to Moimenta da Beira | 924.47 mi (1,487.78 km) |
| Clayton to Moita | 1,098.91 mi (1,768.52 km) |
| Clayton to Moncao | 864.94 mi (1,391.98 km) |
