| Clarksburg to Oerlinghausen | 3,997.99 mi (6,434.14 km) |
| Clarksburg to Oestrich-Winkel | 4,027.94 mi (6,482.35 km) |
| Clarksburg to Offenburg | 4,070.42 mi (6,550.70 km) |
| Clarksburg to Oftersheim | 4,070.11 mi (6,550.20 km) |
| Clarksburg to Ohrdruf | 4,112.01 mi (6,617.64 km) |
| Clarksburg to Ohringen | 4,112.37 mi (6,618.22 km) |
| Clarksburg to Olbernhau | 4,218.45 mi (6,788.94 km) |
| Clarksburg to Olching | 4,217.53 mi (6,787.46 km) |
| Clarksburg to Oldenburg | 3,947.93 mi (6,353.58 km) |
| Clarksburg to Oldenburg in Holstein | 4,015.76 mi (6,462.73 km) |
| Clarksburg to Olfen | 3,954.84 mi (6,364.70 km) |
| Clarksburg to Olpe | 3,992.14 mi (6,424.72 km) |
| Clarksburg to Olsberg | 4,008.33 mi (6,450.79 km) |
| Clarksburg to Oranienburg | 4,148.91 mi (6,677.02 km) |
| Clarksburg to Ortenberg | 4,059.82 mi (6,533.66 km) |
