| Great Falls to Oberkirch | 4,874.45 mi (7,844.67 km) |
| Great Falls to Obernburg am Main | 4,833.50 mi (7,778.76 km) |
| Great Falls to Obernkirchen | 4,701.85 mi (7,566.90 km) |
| Great Falls to Oberschleissheim | 4,987.48 mi (8,026.58 km) |
| Great Falls to Oberstdorf | 4,998.09 mi (8,043.66 km) |
| Great Falls to Obertraubling | 4,964.02 mi (7,988.82 km) |
| Great Falls to Obertshausen | 4,812.71 mi (7,745.31 km) |
| Great Falls to Oberursel | 4,798.25 mi (7,722.04 km) |
| Great Falls to Ochsenfurt | 4,869.29 mi (7,836.36 km) |
| Great Falls to Ochsenhausen | 4,952.36 mi (7,970.06 km) |
| Great Falls to Ochtrup | 4,653.24 mi (7,488.66 km) |
| Great Falls to Odenthal | 4,713.34 mi (7,585.39 km) |
| Great Falls to Oelde | 4,699.10 mi (7,562.47 km) |
| Great Falls to Oelsnitz | 4,883.45 mi (7,859.15 km) |
| Great Falls to Oer-Erkenschwick | 4,684.74 mi (7,539.35 km) |
