| Difficult Run to Cadillac (Michigan) | 556.71 mi (895.94 km) |
| Difficult Run to Caguas (Puerto Rico) | 1,581.26 mi (2,544.80 km) |
| Difficult Run to Cahokia (Illinois) | 691.44 mi (1,112.77 km) |
| Difficult Run to Calabasas (California) | 2,298.23 mi (3,698.64 km) |
| Difficult Run to Caldwell (Idaho) | 2,048.03 mi (3,295.98 km) |
| Difficult Run to Caledonia (Wisconsin) | 612.03 mi (984.96 km) |
| Difficult Run to Calera (Alabama) | 659.03 mi (1,060.61 km) |
| Difficult Run to Calexico (California) | 2,164.37 mi (3,483.22 km) |
| Difficult Run to Calhoun (Georgia) | 519.06 mi (835.34 km) |
| Difficult Run to California (Maryland) | 62.15 mi (100.03 km) |
| Difficult Run to California City (California) | 2,231.85 mi (3,591.82 km) |
| Difficult Run to Callaway (Florida) | 764.32 mi (1,230.05 km) |
| Difficult Run to Calumet City (Illinois) | 569.27 mi (916.15 km) |
| Difficult Run to Calverton (Maryland) | 23.96 mi (38.56 km) |
| Difficult Run to Camano (Washington) | 2,312.82 mi (3,722.12 km) |
