| Merthyr Tudful to Marysville (California) | 5,140.87 mi (8,273.43 km) |
| Merthyr Tudful to Marysville (Ohio) | 3,723.26 mi (5,992.02 km) |
| Merthyr Tudful to Marysville (Washington) | 4,653.26 mi (7,488.70 km) |
| Merthyr Tudful to Maryville (Missouri) | 4,163.66 mi (6,700.76 km) |
| Merthyr Tudful to Maryville (Tennessee) | 3,956.36 mi (6,367.15 km) |
| Merthyr Tudful to Mason (Ohio) | 3,800.59 mi (6,116.46 km) |
| Merthyr Tudful to Mason City (Iowa) | 3,967.57 mi (6,385.18 km) |
| Merthyr Tudful to Massapequa (New York) | 3,303.11 mi (5,315.84 km) |
| Merthyr Tudful to Massapequa Park (New York) | 3,301.64 mi (5,313.48 km) |
| Merthyr Tudful to Massillon (Ohio) | 3,625.10 mi (5,834.04 km) |
| Merthyr Tudful to Mastic (New York) | 3,271.40 mi (5,264.81 km) |
| Merthyr Tudful to Mastic Beach (New York) | 3,272.78 mi (5,267.03 km) |
| Merthyr Tudful to Matteson (Illinois) | 3,837.05 mi (6,175.14 km) |
| Merthyr Tudful to Matthews (North Carolina) | 3,851.95 mi (6,199.12 km) |
| Merthyr Tudful to Mattoon (Illinois) | 3,955.37 mi (6,365.55 km) |
