| Merthyr Tudful to Mountain Brook (Alabama) | 4,177.74 mi (6,723.43 km) |
| Merthyr Tudful to Mountain Home (Arkansas) | 4,263.84 mi (6,861.99 km) |
| Merthyr Tudful to Mountain Home (Idaho) | 4,738.19 mi (7,625.38 km) |
| Merthyr Tudful to Mountain House (California) | 5,218.61 mi (8,398.54 km) |
| Merthyr Tudful to Mountain Park (Georgia) | 4,053.63 mi (6,523.69 km) |
| Merthyr Tudful to Mountain Top (Pennsylvania) | 3,382.78 mi (5,444.06 km) |
| Merthyr Tudful to Mountain View (California) | 5,256.05 mi (8,458.79 km) |
| Merthyr Tudful to Mountlake Terrace (Washington) | 4,673.53 mi (7,521.33 km) |
| Merthyr Tudful to Mukilteo (Washington) | 4,666.84 mi (7,510.56 km) |
| Merthyr Tudful to Muncie (Indiana) | 3,805.28 mi (6,124.01 km) |
| Merthyr Tudful to Mundelein (Illinois) | 3,812.43 mi (6,135.51 km) |
| Merthyr Tudful to Munhall (Pennsylvania) | 3,577.20 mi (5,756.95 km) |
| Merthyr Tudful to Munster (Indiana) | 3,825.95 mi (6,157.26 km) |
| Merthyr Tudful to Murfreesboro (Tennessee) | 4,050.09 mi (6,517.99 km) |
| Merthyr Tudful to Murphy (Texas) | 4,595.30 mi (7,395.42 km) |
