| Chicago to Oberkirch | 4,369.58 mi (7,032.16 km) |
| Chicago to Obernburg am Main | 4,358.87 mi (7,014.92 km) |
| Chicago to Obernkirchen | 4,265.70 mi (6,864.98 km) |
| Chicago to Oberschleissheim | 4,511.82 mi (7,261.07 km) |
| Chicago to Oberstdorf | 4,497.28 mi (7,237.68 km) |
| Chicago to Obertraubling | 4,504.93 mi (7,249.98 km) |
| Chicago to Obertshausen | 4,338.77 mi (6,982.58 km) |
| Chicago to Oberursel | 4,324.09 mi (6,958.95 km) |
| Chicago to Ochsenfurt | 4,400.40 mi (7,081.76 km) |
| Chicago to Ochsenhausen | 4,458.26 mi (7,174.87 km) |
| Chicago to Ochtrup | 4,199.00 mi (6,757.64 km) |
| Chicago to Odenthal | 4,239.21 mi (6,822.35 km) |
| Chicago to Oelde | 4,247.24 mi (6,835.26 km) |
| Chicago to Oelsnitz | 4,446.33 mi (7,155.68 km) |
| Chicago to Oer-Erkenschwick | 4,221.74 mi (6,794.24 km) |
