| Merthyr Tudful to Smyrna (Delaware) | 3,450.80 mi (5,553.53 km) |
| Merthyr Tudful to Smyrna (Georgia) | 4,068.60 mi (6,547.78 km) |
| Merthyr Tudful to Smyrna (Tennessee) | 4,048.96 mi (6,516.17 km) |
| Merthyr Tudful to Snellville (Georgia) | 4,047.89 mi (6,514.45 km) |
| Merthyr Tudful to Snoqualmie (Washington) | 4,675.48 mi (7,524.46 km) |
| Merthyr Tudful to Snyder (Texas) | 4,777.18 mi (7,688.14 km) |
| Merthyr Tudful to Socastee (South Carolina) | 3,849.09 mi (6,194.52 km) |
| Merthyr Tudful to Socorro (Texas) | 5,035.52 mi (8,103.89 km) |
| Merthyr Tudful to Soddy-Daisy (Tennessee) | 4,028.34 mi (6,482.99 km) |
| Merthyr Tudful to Solana Beach (California) | 5,350.93 mi (8,611.49 km) |
| Merthyr Tudful to Soledad (California) | 5,287.94 mi (8,510.12 km) |
| Merthyr Tudful to Solon (Ohio) | 3,594.94 mi (5,785.50 km) |
| Merthyr Tudful to Somers Point (New Jersey) | 3,408.45 mi (5,485.38 km) |
| Merthyr Tudful to Somerset (Kentucky) | 3,918.78 mi (6,306.67 km) |
| Merthyr Tudful to Somerset (New Jersey) | 3,352.32 mi (5,395.05 km) |
