| Portland to Oerlinghausen | 5,106.36 mi (8,217.89 km) |
| Portland to Oestrich-Winkel | 5,204.08 mi (8,375.16 km) |
| Portland to Offenburg | 5,291.04 mi (8,515.11 km) |
| Portland to Oftersheim | 5,254.78 mi (8,456.76 km) |
| Portland to Ohrdruf | 5,220.53 mi (8,401.63 km) |
| Portland to Ohringen | 5,286.93 mi (8,508.48 km) |
| Portland to Olbernhau | 5,288.43 mi (8,510.91 km) |
| Portland to Olching | 5,389.21 mi (8,673.09 km) |
| Portland to Oldenburg | 5,028.00 mi (8,091.79 km) |
| Portland to Oldenburg in Holstein | 5,020.25 mi (8,079.32 km) |
| Portland to Olfen | 5,090.44 mi (8,192.27 km) |
| Portland to Olpe | 5,141.43 mi (8,274.33 km) |
| Portland to Olsberg | 5,137.70 mi (8,268.33 km) |
| Portland to Oranienburg | 5,161.68 mi (8,306.92 km) |
| Portland to Ortenberg | 5,208.91 mi (8,382.93 km) |
