| Difficult Run to Cold Springs (Nevada) | 2,258.28 mi (3,634.35 km) |
| Difficult Run to Coldwater (Michigan) | 453.90 mi (730.48 km) |
| Difficult Run to Colesville (Maryland) | 22.04 mi (35.47 km) |
| Difficult Run to College (Alaska) | 3,263.57 mi (5,252.21 km) |
| Difficult Run to College Park (Georgia) | 537.74 mi (865.41 km) |
| Difficult Run to College Park (Maryland) | 23.15 mi (37.26 km) |
| Difficult Run to College Station (Texas) | 1,216.19 mi (1,957.28 km) |
| Difficult Run to Collegedale (Tennessee) | 501.16 mi (806.54 km) |
| Difficult Run to Colleyville (Texas) | 1,180.54 mi (1,899.89 km) |
| Difficult Run to Collierville (Tennessee) | 731.20 mi (1,176.75 km) |
| Difficult Run to Collinsville (Illinois) | 681.39 mi (1,096.60 km) |
| Difficult Run to Colonia (New Jersey) | 198.98 mi (320.22 km) |
| Difficult Run to Colonial Heights (Virginia) | 113.11 mi (182.03 km) |
| Difficult Run to Colonial Park (Pennsylvania) | 100.72 mi (162.10 km) |
| Difficult Run to Colorado Springs (Colorado) | 1,468.77 mi (2,363.75 km) |
