| Potomac to McHenry (Illinois) | 624.70 mi (1,005.36 km) |
| Potomac to McKeesport (Pennsylvania) | 168.12 mi (270.57 km) |
| Potomac to McKinleyville (California) | 2,456.18 mi (3,952.84 km) |
| Potomac to McKinney (Texas) | 1,155.95 mi (1,860.32 km) |
| Potomac to McLean (Virginia) | 4.87 mi (7.84 km) |
| Potomac to McMinnville (Oregon) | 2,363.32 mi (3,803.40 km) |
| Potomac to McMinnville (Tennessee) | 524.39 mi (843.92 km) |
| Potomac to McNair (Virginia) | 12.45 mi (20.03 km) |
| Potomac to McPherson (Kansas) | 1,102.27 mi (1,773.93 km) |
| Potomac to Mead Valley (California) | 2,239.15 mi (3,603.56 km) |
| Potomac to Meadow Woods (Florida) | 772.97 mi (1,243.97 km) |
| Potomac to Meadowbrook (Virginia) | 110.49 mi (177.82 km) |
| Potomac to Meadville (Pennsylvania) | 239.33 mi (385.16 km) |
| Potomac to Mebane (North Carolina) | 232.20 mi (373.69 km) |
| Potomac to Mechanicsville (Virginia) | 96.29 mi (154.96 km) |
