| Difficult Run to Carrollwood (Florida) | 805.87 mi (1,296.92 km) |
| Difficult Run to Carson (California) | 2,283.41 mi (3,674.79 km) |
| Difficult Run to Carson City (Nevada) | 2,254.70 mi (3,628.59 km) |
| Difficult Run to Carteret (New Jersey) | 202.41 mi (325.75 km) |
| Difficult Run to Cartersville (Georgia) | 527.29 mi (848.59 km) |
| Difficult Run to Carthage (Missouri) | 930.43 mi (1,497.38 km) |
| Difficult Run to Cary (Illinois) | 615.77 mi (990.98 km) |
| Difficult Run to Cary (North Carolina) | 230.22 mi (370.50 km) |
| Difficult Run to Casa de Oro-Mount Helix (California) | 2,241.56 mi (3,607.44 km) |
| Difficult Run to Casa Grande (Arizona) | 1,957.92 mi (3,150.96 km) |
| Difficult Run to Casas Adobes (Arizona) | 1,932.55 mi (3,110.14 km) |
| Difficult Run to Cascades (Virginia) | 10.24 mi (16.47 km) |
| Difficult Run to Casper (Wyoming) | 1,530.22 mi (2,462.65 km) |
| Difficult Run to Casselberry (Florida) | 743.15 mi (1,195.98 km) |
| Difficult Run to Castaic (California) | 2,288.01 mi (3,682.20 km) |
