| Mason City to Oberkirch | 4,511.45 mi (7,260.48 km) |
| Mason City to Obernburg am Main | 4,493.34 mi (7,231.33 km) |
| Mason City to Obernkirchen | 4,389.99 mi (7,065.01 km) |
| Mason City to Oberschleissheim | 4,647.86 mi (7,480.00 km) |
| Mason City to Oberstdorf | 4,639.25 mi (7,466.15 km) |
| Mason City to Obertraubling | 4,636.92 mi (7,462.40 km) |
| Mason City to Obertshausen | 4,472.90 mi (7,198.43 km) |
| Mason City to Oberursel | 4,458.14 mi (7,174.68 km) |
| Mason City to Ochsenfurt | 4,533.85 mi (7,296.52 km) |
| Mason City to Ochsenhausen | 4,598.28 mi (7,400.22 km) |
| Mason City to Ochtrup | 4,327.08 mi (6,963.75 km) |
| Mason City to Odenthal | 4,372.49 mi (7,036.85 km) |
| Mason City to Oelde | 4,375.18 mi (7,041.17 km) |
| Mason City to Oelsnitz | 4,572.51 mi (7,358.74 km) |
| Mason City to Oer-Erkenschwick | 4,352.16 mi (7,004.12 km) |
