| Difficult Run to Coudekerque-Branche | 3,791.29 mi (6,101.49 km) |
| Difficult Run to Coueron | 3,709.74 mi (5,970.26 km) |
| Difficult Run to Coulommiers | 3,875.84 mi (6,237.56 km) |
| Difficult Run to Courbevoic | 3,838.72 mi (6,177.83 km) |
| Difficult Run to Courcouronnes | 3,853.26 mi (6,201.22 km) |
| Difficult Run to Cournon-d'Auvergne | 3,964.91 mi (6,380.91 km) |
| Difficult Run to Courrieres | 3,827.96 mi (6,160.51 km) |
| Difficult Run to Coutras | 3,836.50 mi (6,174.25 km) |
| Difficult Run to Couzeix | 3,874.85 mi (6,235.96 km) |
| Difficult Run to Cran-Gevrier | 4,087.00 mi (6,577.39 km) |
| Difficult Run to Craponne | 4,031.67 mi (6,488.35 km) |
| Difficult Run to Creil | 3,839.14 mi (6,178.50 km) |
| Difficult Run to Crepy-en-Valois | 3,856.68 mi (6,206.72 km) |
| Difficult Run to Crest | 4,075.02 mi (6,558.12 km) |
| Difficult Run to Creteil | 3,850.32 mi (6,196.50 km) |
