| Merthyr Tudful to Castle Rock (Colorado) | 4,576.58 mi (7,365.30 km) |
| Merthyr Tudful to Castro Valley (California) | 5,237.85 mi (8,429.51 km) |
| Merthyr Tudful to Catalina Foothills (Arizona) | 5,168.04 mi (8,317.15 km) |
| Merthyr Tudful to Cataño (Puerto Rico) | 4,066.70 mi (6,544.71 km) |
| Merthyr Tudful to Cathedral City (California) | 5,277.00 mi (8,492.52 km) |
| Merthyr Tudful to Catonsville (Maryland) | 3,498.71 mi (5,630.63 km) |
| Merthyr Tudful to Cave Spring (Virginia) | 3,724.85 mi (5,994.57 km) |
| Merthyr Tudful to Cayce (South Carolina) | 3,921.40 mi (6,310.88 km) |
| Merthyr Tudful to Cayey (Puerto Rico) | 4,084.57 mi (6,573.48 km) |
| Merthyr Tudful to Cedar City (Utah) | 4,951.09 mi (7,968.00 km) |
| Merthyr Tudful to Cedar Falls (Iowa) | 3,969.29 mi (6,387.95 km) |
| Merthyr Tudful to Cedar Hill (Texas) | 4,631.29 mi (7,453.34 km) |
| Merthyr Tudful to Cedar Lake (Indiana) | 3,831.55 mi (6,166.28 km) |
| Merthyr Tudful to Cedar Mill (Oregon) | 4,814.06 mi (7,747.47 km) |
| Merthyr Tudful to Cedar Park (Texas) | 4,771.75 mi (7,679.39 km) |
