| Frederick to Oerlinghausen | 3,993.81 mi (6,427.41 km) |
| Frederick to Oestrich-Winkel | 4,024.41 mi (6,476.65 km) |
| Frederick to Offenburg | 4,067.34 mi (6,545.76 km) |
| Frederick to Oftersheim | 4,066.70 mi (6,544.73 km) |
| Frederick to Ohrdruf | 4,107.98 mi (6,611.16 km) |
| Frederick to Ohringen | 4,108.93 mi (6,612.68 km) |
| Frederick to Olbernhau | 4,214.23 mi (6,782.14 km) |
| Frederick to Olching | 4,214.20 mi (6,782.10 km) |
| Frederick to Oldenburg | 3,943.43 mi (6,346.34 km) |
| Frederick to Oldenburg in Holstein | 4,010.70 mi (6,454.60 km) |
| Frederick to Olfen | 3,950.84 mi (6,358.26 km) |
| Frederick to Olpe | 3,988.31 mi (6,418.56 km) |
| Frederick to Olsberg | 4,004.35 mi (6,444.38 km) |
| Frederick to Oranienburg | 4,144.10 mi (6,669.29 km) |
| Frederick to Ortenberg | 4,056.09 mi (6,527.64 km) |
