| Mason City to Octeville | 4,108.09 mi (6,611.34 km) |
| Mason City to Oignies | 4,248.25 mi (6,836.90 km) |
| Mason City to Oissel | 4,221.78 mi (6,794.31 km) |
| Mason City to Olivet | 4,309.93 mi (6,936.16 km) |
| Mason City to Ollioules | 4,658.49 mi (7,497.12 km) |
| Mason City to Olonne-sur-Mer | 4,218.91 mi (6,789.67 km) |
| Mason City to Oloron-Sainte-Marie | 4,396.95 mi (7,076.20 km) |
| Mason City to Onet Village | 4,478.23 mi (7,207.01 km) |
| Mason City to Onnaing | 4,273.35 mi (6,877.30 km) |
| Mason City to Orange | 4,575.02 mi (7,362.78 km) |
| Mason City to Orchies | 4,257.13 mi (6,851.18 km) |
| Mason City to Orleans | 4,308.72 mi (6,934.22 km) |
| Mason City to Orly | 4,293.76 mi (6,910.13 km) |
| Mason City to Ormesson-sur-Marne | 4,297.54 mi (6,916.23 km) |
| Mason City to Orsay | 4,287.87 mi (6,900.66 km) |
