| Chicago to Octeville | 3,953.29 mi (6,362.20 km) |
| Chicago to Oignies | 4,105.11 mi (6,606.53 km) |
| Chicago to Oissel | 4,070.39 mi (6,550.66 km) |
| Chicago to Olivet | 4,153.67 mi (6,684.69 km) |
| Chicago to Ollioules | 4,491.21 mi (7,227.90 km) |
| Chicago to Olonne-sur-Mer | 4,050.54 mi (6,518.72 km) |
| Chicago to Oloron-Sainte-Marie | 4,217.32 mi (6,787.13 km) |
| Chicago to Onet Village | 4,309.18 mi (6,934.95 km) |
| Chicago to Onnaing | 4,130.92 mi (6,648.08 km) |
| Chicago to Orange | 4,409.41 mi (7,096.27 km) |
| Chicago to Orchies | 4,114.45 mi (6,621.56 km) |
| Chicago to Orleans | 4,152.64 mi (6,683.04 km) |
| Chicago to Orly | 4,142.10 mi (6,666.07 km) |
| Chicago to Ormesson-sur-Marne | 4,146.33 mi (6,672.87 km) |
| Chicago to Orsay | 4,135.65 mi (6,655.69 km) |
