| Port Huron to Oberkirch | 4,115.99 mi (6,624.04 km) |
| Port Huron to Obernburg am Main | 4,108.79 mi (6,612.47 km) |
| Port Huron to Obernkirchen | 4,020.90 mi (6,471.02 km) |
| Port Huron to Oberschleissheim | 4,260.70 mi (6,856.94 km) |
| Port Huron to Oberstdorf | 4,243.42 mi (6,829.13 km) |
| Port Huron to Obertraubling | 4,255.78 mi (6,849.02 km) |
| Port Huron to Obertshausen | 4,088.90 mi (6,580.46 km) |
| Port Huron to Oberursel | 4,074.29 mi (6,556.94 km) |
| Port Huron to Ochsenfurt | 4,150.75 mi (6,679.98 km) |
| Port Huron to Ochsenhausen | 4,205.36 mi (6,767.87 km) |
| Port Huron to Ochtrup | 3,952.43 mi (6,360.81 km) |
| Port Huron to Odenthal | 3,989.96 mi (6,421.22 km) |
| Port Huron to Oelde | 4,000.62 mi (6,438.38 km) |
| Port Huron to Oelsnitz | 4,200.19 mi (6,759.56 km) |
| Port Huron to Oer-Erkenschwick | 3,973.94 mi (6,395.44 km) |
