| Difficult Run to Cibolo (Texas) | 1,350.65 mi (2,173.67 km) |
| Difficult Run to Cicero (Illinois) | 584.11 mi (940.03 km) |
| Difficult Run to Cimarron Hills (Colorado) | 1,465.61 mi (2,358.66 km) |
| Difficult Run to Cincinnati (Ohio) | 384.54 mi (618.86 km) |
| Difficult Run to Cinco Ranch (Texas) | 1,223.16 mi (1,968.49 km) |
| Difficult Run to Circleville (Ohio) | 302.77 mi (487.26 km) |
| Difficult Run to Citrus (California) | 2,256.96 mi (3,632.22 km) |
| Difficult Run to Citrus Heights (California) | 2,342.66 mi (3,770.14 km) |
| Difficult Run to Citrus Park (Florida) | 805.90 mi (1,296.96 km) |
| Difficult Run to Claiborne (Louisiana) | 940.31 mi (1,513.29 km) |
| Difficult Run to Claremont (California) | 2,247.40 mi (3,616.84 km) |
| Difficult Run to Claremont (New Hampshire) | 404.40 mi (650.82 km) |
| Difficult Run to Claremore (Oklahoma) | 1,013.67 mi (1,631.35 km) |
| Difficult Run to Clarksburg (Maryland) | 22.74 mi (36.59 km) |
| Difficult Run to Clarksburg (West Virginia) | 161.78 mi (260.36 km) |
