| Merthyr Tudful to Rockville (Maryland) | 3,523.70 mi (5,670.85 km) |
| Merthyr Tudful to Rockville Centre (New York) | 3,310.15 mi (5,327.18 km) |
| Merthyr Tudful to Rockwall (Texas) | 4,593.73 mi (7,392.89 km) |
| Merthyr Tudful to Rocky Mount (North Carolina) | 3,691.92 mi (5,941.58 km) |
| Merthyr Tudful to Rocky Point (New York) | 3,269.69 mi (5,262.06 km) |
| Merthyr Tudful to Rocky River (Ohio) | 3,607.65 mi (5,805.95 km) |
| Merthyr Tudful to Roessleville (New York) | 3,231.08 mi (5,199.92 km) |
| Merthyr Tudful to Rogers (Arkansas) | 4,333.65 mi (6,974.34 km) |
| Merthyr Tudful to Rogers (Minnesota) | 3,886.70 mi (6,255.04 km) |
| Merthyr Tudful to Rohnert Park (California) | 5,220.52 mi (8,401.61 km) |
| Merthyr Tudful to Rolla (Missouri) | 4,160.94 mi (6,696.39 km) |
| Merthyr Tudful to Rolling Meadows (Illinois) | 3,821.89 mi (6,150.74 km) |
| Merthyr Tudful to Roma (Texas) | 5,033.07 mi (8,099.94 km) |
| Merthyr Tudful to Rome (Georgia) | 4,076.53 mi (6,560.53 km) |
| Merthyr Tudful to Rome (New York) | 3,277.74 mi (5,275.02 km) |
