| Chicago to Nuth | 4,197.90 mi (6,755.87 km) |
| Chicago to Oegstgeest | 4,100.81 mi (6,599.61 km) |
| Chicago to Oirschot | 4,155.42 mi (6,687.50 km) |
| Chicago to Oisterwijk | 4,148.78 mi (6,676.81 km) |
| Chicago to Oldebroek | 4,143.66 mi (6,668.58 km) |
| Chicago to Oldenzaal | 4,185.72 mi (6,736.26 km) |
| Chicago to Ommen | 4,159.94 mi (6,694.77 km) |
| Chicago to Oosterend | 4,130.11 mi (6,646.76 km) |
| Chicago to Oosterhout | 4,134.01 mi (6,653.04 km) |
| Chicago to Oosterwolde | 4,138.62 mi (6,660.47 km) |
| Chicago to Oostzaan | 4,107.36 mi (6,610.15 km) |
| Chicago to Opmeer | 4,100.52 mi (6,599.15 km) |
| Chicago to Oss | 4,153.92 mi (6,685.09 km) |
| Chicago to Oud-Beijerland | 4,111.07 mi (6,616.13 km) |
| Chicago to Oudenbosch | 4,123.59 mi (6,636.27 km) |
