| Philadelphia to Oerlinghausen | 3,878.08 mi (6,241.17 km) |
| Philadelphia to Oestrich-Winkel | 3,906.59 mi (6,287.05 km) |
| Philadelphia to Offenburg | 3,948.16 mi (6,353.95 km) |
| Philadelphia to Oftersheim | 3,948.48 mi (6,354.47 km) |
| Philadelphia to Ohrdruf | 3,991.72 mi (6,424.06 km) |
| Philadelphia to Ohringen | 3,990.81 mi (6,422.59 km) |
| Philadelphia to Olbernhau | 4,098.61 mi (6,596.07 km) |
| Philadelphia to Olching | 4,095.74 mi (6,591.46 km) |
| Philadelphia to Oldenburg | 3,828.81 mi (6,161.88 km) |
| Philadelphia to Oldenburg in Holstein | 3,898.12 mi (6,273.43 km) |
| Philadelphia to Olfen | 3,834.51 mi (6,171.05 km) |
| Philadelphia to Olpe | 3,871.41 mi (6,230.43 km) |
| Philadelphia to Olsberg | 3,887.95 mi (6,257.06 km) |
| Philadelphia to Oranienburg | 4,030.56 mi (6,486.55 km) |
| Philadelphia to Ortenberg | 3,938.90 mi (6,339.04 km) |
