| Potomac to Cocentaina | 3,993.75 mi (6,427.33 km) |
| Potomac to Coin | 3,846.66 mi (6,190.60 km) |
| Potomac to Colindres | 3,717.62 mi (5,982.92 km) |
| Potomac to Collado-Villalba | 3,766.50 mi (6,061.60 km) |
| Potomac to Colmenar Viejo | 3,777.39 mi (6,079.12 km) |
| Potomac to Colmenarejo | 3,768.13 mi (6,064.22 km) |
| Potomac to Conil de la Frontera | 3,792.31 mi (6,103.13 km) |
| Potomac to Consuegra | 3,819.38 mi (6,146.70 km) |
| Potomac to Corbera de Llobregat | 4,023.97 mi (6,475.95 km) |
| Potomac to Cordoba | 3,808.51 mi (6,129.21 km) |
| Potomac to Coria del Rio | 3,763.52 mi (6,056.79 km) |
| Potomac to Crevillente | 3,991.38 mi (6,423.51 km) |
| Potomac to Cuarte de Huerva | 3,885.98 mi (6,253.88 km) |
| Potomac to Cubellas | 4,018.27 mi (6,466.78 km) |
| Potomac to Cuellar | 3,730.62 mi (6,003.85 km) |
