| Mason City to Oerlinghausen | 4,387.25 mi (7,060.59 km) |
| Mason City to Oestrich-Winkel | 4,446.44 mi (7,155.86 km) |
| Mason City to Offenburg | 4,508.87 mi (7,256.33 km) |
| Mason City to Oftersheim | 4,493.73 mi (7,231.96 km) |
| Mason City to Ohrdruf | 4,505.84 mi (7,251.46 km) |
| Mason City to Ohringen | 4,533.40 mi (7,295.81 km) |
| Mason City to Olbernhau | 4,600.61 mi (7,403.97 km) |
| Mason City to Olching | 4,641.27 mi (7,469.40 km) |
| Mason City to Oldenburg | 4,323.39 mi (6,957.82 km) |
| Mason City to Oldenburg in Holstein | 4,362.67 mi (7,021.04 km) |
| Mason City to Olfen | 4,353.68 mi (7,006.56 km) |
| Mason City to Olpe | 4,398.14 mi (7,078.11 km) |
| Mason City to Olsberg | 4,406.71 mi (7,091.91 km) |
| Mason City to Oranienburg | 4,504.81 mi (7,249.78 km) |
| Mason City to Ortenberg | 4,468.37 mi (7,191.14 km) |
