| Mason City to Opole | 4,750.96 mi (7,645.93 km) |
| Mason City to Orzesze | 4,801.62 mi (7,727.46 km) |
| Mason City to Osowa | 4,591.30 mi (7,388.99 km) |
| Mason City to Ostroda | 4,669.94 mi (7,515.54 km) |
| Mason City to Ostroleka | 4,747.74 mi (7,640.75 km) |
| Mason City to Ostrow Mazowiecka | 4,770.57 mi (7,677.50 km) |
| Mason City to Ostrow Wielkopolski | 4,701.01 mi (7,565.54 km) |
| Mason City to Ostrowiec Swietokrzyski | 4,846.80 mi (7,800.18 km) |
| Mason City to Ostrzeszow | 4,715.62 mi (7,589.06 km) |
| Mason City to Oswiecim | 4,822.04 mi (7,760.32 km) |
| Mason City to Otwock | 4,784.98 mi (7,700.68 km) |
| Mason City to Ozarow Mazowiecki | 4,766.04 mi (7,670.21 km) |
| Mason City to Ozimek | 4,759.59 mi (7,659.82 km) |
| Mason City to Ozorkow | 4,731.73 mi (7,614.98 km) |
| Mason City to Pabianice | 4,749.92 mi (7,644.26 km) |
