| Merthyr Tudful to Security-Widefield (Colorado) | 4,604.12 mi (7,409.62 km) |
| Merthyr Tudful to Sedalia (Missouri) | 4,180.96 mi (6,728.61 km) |
| Merthyr Tudful to Sedro-Woolley (Washington) | 4,631.28 mi (7,453.32 km) |
| Merthyr Tudful to Seguin (Texas) | 4,825.45 mi (7,765.81 km) |
| Merthyr Tudful to Selden (New York) | 3,276.96 mi (5,273.76 km) |
| Merthyr Tudful to Selma (Alabama) | 4,242.26 mi (6,827.26 km) |
| Merthyr Tudful to Selma (California) | 5,226.14 mi (8,410.66 km) |
| Merthyr Tudful to Selma (Texas) | 4,839.22 mi (7,787.98 km) |
| Merthyr Tudful to Seminole (Florida) | 4,293.02 mi (6,908.94 km) |
| Merthyr Tudful to Seven Hills (Ohio) | 3,604.52 mi (5,800.91 km) |
| Merthyr Tudful to Seven Oaks (South Carolina) | 3,920.72 mi (6,309.79 km) |
| Merthyr Tudful to Severn (Maryland) | 3,502.51 mi (5,636.75 km) |
| Merthyr Tudful to Severna Park (Maryland) | 3,499.45 mi (5,631.82 km) |
| Merthyr Tudful to Sevierville (Tennessee) | 3,932.95 mi (6,329.47 km) |
| Merthyr Tudful to Seymour (Indiana) | 3,882.75 mi (6,248.69 km) |
