| Difficult Run to McKeesport (Pennsylvania) | 166.00 mi (267.15 km) |
| Difficult Run to McKinleyville (California) | 2,450.87 mi (3,944.29 km) |
| Difficult Run to McKinney (Texas) | 1,146.08 mi (1,844.44 km) |
| Difficult Run to McLean (Virginia) | 8.71 mi (14.02 km) |
| Difficult Run to McMinnville (Oregon) | 2,359.30 mi (3,796.92 km) |
| Difficult Run to McMinnville (Tennessee) | 513.78 mi (826.85 km) |
| Difficult Run to McNair (Virginia) | 4.88 mi (7.85 km) |
| Difficult Run to McPherson (Kansas) | 1,094.67 mi (1,761.70 km) |
| Difficult Run to Mead Valley (California) | 2,231.43 mi (3,591.14 km) |
| Difficult Run to Meadow Woods (Florida) | 762.95 mi (1,227.85 km) |
| Difficult Run to Meadowbrook (Virginia) | 101.90 mi (164.00 km) |
| Difficult Run to Meadville (Pennsylvania) | 240.34 mi (386.79 km) |
| Difficult Run to Mebane (North Carolina) | 221.39 mi (356.29 km) |
| Difficult Run to Mechanicsville (Virginia) | 88.12 mi (141.81 km) |
| Difficult Run to Medford (Massachusetts) | 407.39 mi (655.62 km) |
