| Merthyr Tudful to Caguas (Puerto Rico) | 4,073.15 mi (6,555.09 km) |
| Merthyr Tudful to Cahokia (Illinois) | 4,069.58 mi (6,549.36 km) |
| Merthyr Tudful to Calabasas (California) | 5,333.33 mi (8,583.16 km) |
| Merthyr Tudful to Caldwell (Idaho) | 4,739.82 mi (7,628.01 km) |
| Merthyr Tudful to Caledonia (Wisconsin) | 3,783.22 mi (6,088.50 km) |
| Merthyr Tudful to Calera (Alabama) | 4,195.64 mi (6,752.24 km) |
| Merthyr Tudful to Calexico (California) | 5,308.44 mi (8,543.11 km) |
| Merthyr Tudful to Calhoun (Georgia) | 4,055.57 mi (6,526.81 km) |
| Merthyr Tudful to California (Maryland) | 3,531.64 mi (5,683.63 km) |
| Merthyr Tudful to California City (California) | 5,249.62 mi (8,448.44 km) |
| Merthyr Tudful to Callaway (Florida) | 4,294.44 mi (6,911.23 km) |
| Merthyr Tudful to Calumet City (Illinois) | 3,824.69 mi (6,155.25 km) |
| Merthyr Tudful to Calverton (Maryland) | 3,516.37 mi (5,659.04 km) |
| Merthyr Tudful to Camano (Washington) | 4,655.87 mi (7,492.90 km) |
| Merthyr Tudful to Camarillo (California) | 5,340.38 mi (8,594.52 km) |
