| Difficult Run to Clemson (South Carolina) | 419.81 mi (675.62 km) |
| Difficult Run to Clermont (Florida) | 758.98 mi (1,221.46 km) |
| Difficult Run to Cleveland (Mississippi) | 824.63 mi (1,327.12 km) |
| Difficult Run to Cleveland (Ohio) | 289.70 mi (466.23 km) |
| Difficult Run to Cleveland (Tennessee) | 487.82 mi (785.07 km) |
| Difficult Run to Cleveland Heights (Ohio) | 286.32 mi (460.79 km) |
| Difficult Run to Cliffside Park (New Jersey) | 222.12 mi (357.46 km) |
| Difficult Run to Clifton (Colorado) | 1,662.69 mi (2,675.84 km) |
| Difficult Run to Clifton (New Jersey) | 216.69 mi (348.72 km) |
| Difficult Run to Clinton (Iowa) | 707.71 mi (1,138.95 km) |
| Difficult Run to Clinton (Maryland) | 25.94 mi (41.74 km) |
| Difficult Run to Clinton (Mississippi) | 857.25 mi (1,379.61 km) |
| Difficult Run to Clinton (Utah) | 1,831.37 mi (2,947.30 km) |
| Difficult Run to Clive (Iowa) | 885.97 mi (1,425.84 km) |
| Difficult Run to Cloquet (Minnesota) | 936.16 mi (1,506.61 km) |
