| Potomac to Mangualde | 3,586.43 mi (5,771.79 km) |
| Potomac to Marco de Canavezes | 3,552.53 mi (5,717.25 km) |
| Potomac to Marinha Grande | 3,551.84 mi (5,716.13 km) |
| Potomac to Massama | 3,561.67 mi (5,731.95 km) |
| Potomac to Matosinhos | 3,525.96 mi (5,674.49 km) |
| Potomac to Mealhada | 3,558.76 mi (5,727.27 km) |
| Potomac to Melgaco | 3,523.33 mi (5,670.25 km) |
| Potomac to Melres | 3,543.45 mi (5,702.63 km) |
| Potomac to Mira | 3,543.65 mi (5,702.96 km) |
| Potomac to Miranda do Corvo | 3,571.92 mi (5,748.44 km) |
| Potomac to Mirandela | 3,591.33 mi (5,779.70 km) |
| Potomac to Mogadouro | 3,617.61 mi (5,821.99 km) |
| Potomac to Moimenta da Beira | 3,583.71 mi (5,767.42 km) |
| Potomac to Moita | 3,579.02 mi (5,759.88 km) |
| Potomac to Moncao | 3,514.20 mi (5,655.56 km) |
