| Great Falls to Oerlinghausen | 4,705.89 mi (7,573.41 km) |
| Great Falls to Oestrich-Winkel | 4,793.14 mi (7,713.82 km) |
| Great Falls to Offenburg | 4,873.75 mi (7,843.55 km) |
| Great Falls to Oftersheim | 4,843.41 mi (7,794.72 km) |
| Great Falls to Ohrdruf | 4,822.84 mi (7,761.62 km) |
| Great Falls to Ohringen | 4,878.21 mi (7,850.72 km) |
| Great Falls to Olbernhau | 4,899.90 mi (7,885.63 km) |
| Great Falls to Olching | 4,983.38 mi (8,019.98 km) |
| Great Falls to Oldenburg | 4,630.97 mi (7,452.82 km) |
| Great Falls to Oldenburg in Holstein | 4,637.63 mi (7,463.55 km) |
| Great Falls to Olfen | 4,684.42 mi (7,538.84 km) |
| Great Falls to Olpe | 4,734.06 mi (7,618.74 km) |
| Great Falls to Olsberg | 4,734.01 mi (7,618.66 km) |
| Great Falls to Oranienburg | 4,781.17 mi (7,694.55 km) |
| Great Falls to Ortenberg | 4,803.20 mi (7,730.00 km) |
