| Difficult Run to Cloverleaf (Texas) | 1,192.74 mi (1,919.53 km) |
| Difficult Run to Cloverly (Maryland) | 23.42 mi (37.69 km) |
| Difficult Run to Clovis (California) | 2,292.97 mi (3,690.18 km) |
| Difficult Run to Clovis (New Mexico) | 1,459.92 mi (2,349.51 km) |
| Difficult Run to Clute (Texas) | 1,235.53 mi (1,988.39 km) |
| Difficult Run to Coachella (California) | 2,173.61 mi (3,498.09 km) |
| Difficult Run to Coalinga (California) | 2,341.09 mi (3,767.62 km) |
| Difficult Run to Coamo (Puerto Rico) | 1,582.92 mi (2,547.46 km) |
| Difficult Run to Coatesville (Pennsylvania) | 110.64 mi (178.06 km) |
| Difficult Run to Cockeysville (Maryland) | 55.46 mi (89.26 km) |
| Difficult Run to Cocoa (Florida) | 752.82 mi (1,211.55 km) |
| Difficult Run to Cocoa Beach (Florida) | 754.08 mi (1,213.57 km) |
| Difficult Run to Coconut Creek (Florida) | 887.41 mi (1,428.15 km) |
| Difficult Run to Coeur d'Alene (Idaho) | 2,049.69 mi (3,298.66 km) |
| Difficult Run to Cohoes (New York) | 328.18 mi (528.15 km) |
