| South Portland to Oberkirch | 3,602.94 mi (5,798.38 km) |
| South Portland to Obernburg am Main | 3,606.41 mi (5,803.96 km) |
| South Portland to Obernkirchen | 3,534.89 mi (5,688.85 km) |
| South Portland to Oberschleissheim | 3,754.10 mi (6,041.64 km) |
| South Portland to Oberstdorf | 3,728.71 mi (6,000.78 km) |
| South Portland to Obertraubling | 3,755.04 mi (6,043.15 km) |
| South Portland to Obertshausen | 3,587.29 mi (5,773.18 km) |
| South Portland to Oberursel | 3,572.99 mi (5,750.17 km) |
| South Portland to Ochsenfurt | 3,649.29 mi (5,872.96 km) |
| South Portland to Ochsenhausen | 3,693.81 mi (5,944.62 km) |
| South Portland to Ochtrup | 3,461.75 mi (5,571.15 km) |
| South Portland to Odenthal | 3,490.96 mi (5,618.16 km) |
| South Portland to Oelde | 3,509.41 mi (5,647.85 km) |
| South Portland to Oelsnitz | 3,708.71 mi (5,968.59 km) |
| South Portland to Oer-Erkenschwick | 3,479.43 mi (5,599.61 km) |
