| Difficult Run to Carlsbad (California) | 2,249.11 mi (3,619.59 km) |
| Difficult Run to Carlsbad (New Mexico) | 1,568.63 mi (2,524.47 km) |
| Difficult Run to Carmel (Indiana) | 475.06 mi (764.54 km) |
| Difficult Run to Carmichael (California) | 2,345.75 mi (3,775.12 km) |
| Difficult Run to Carney (Maryland) | 56.19 mi (90.42 km) |
| Difficult Run to Carnot-Moon (Pennsylvania) | 189.10 mi (304.33 km) |
| Difficult Run to Carol Stream (Illinois) | 603.87 mi (971.83 km) |
| Difficult Run to Carolina (Puerto Rico) | 1,571.79 mi (2,529.55 km) |
| Difficult Run to Carolina Forest (South Carolina) | 365.43 mi (588.09 km) |
| Difficult Run to Carpentersville (Illinois) | 615.82 mi (991.06 km) |
| Difficult Run to Carpinteria (California) | 2,337.15 mi (3,761.28 km) |
| Difficult Run to Carrboro (North Carolina) | 226.70 mi (364.83 km) |
| Difficult Run to Carroll (Iowa) | 944.38 mi (1,519.83 km) |
| Difficult Run to Carrollton (Georgia) | 566.15 mi (911.14 km) |
| Difficult Run to Carrollton (Texas) | 1,164.62 mi (1,874.27 km) |
