| Chicago to Olympia Heights (Florida) | 1,189.43 mi (1,914.20 km) |
| Chicago to Omaha (Nebraska) | 434.25 mi (698.85 km) |
| Chicago to On Top of the World Designated Place (Florida) | 930.15 mi (1,496.93 km) |
| Chicago to Onalaska (Wisconsin) | 227.72 mi (366.48 km) |
| Chicago to Oneida (New York) | 618.36 mi (995.15 km) |
| Chicago to Oneonta (New York) | 647.31 mi (1,041.74 km) |
| Chicago to Ontario (California) | 1,706.96 mi (2,747.09 km) |
| Chicago to Ontario (Oregon) | 1,481.52 mi (2,384.27 km) |
| Chicago to Opa-locka (Florida) | 1,179.64 mi (1,898.45 km) |
| Chicago to Opelika (Alabama) | 646.55 mi (1,040.52 km) |
| Chicago to Opelousas (Louisiana) | 818.82 mi (1,317.76 km) |
| Chicago to Orange (California) | 1,725.42 mi (2,776.79 km) |
| Chicago to Orange (Texas) | 877.17 mi (1,411.66 km) |
| Chicago to Orange City (Florida) | 960.85 mi (1,546.34 km) |
| Chicago to Orangeburg (South Carolina) | 686.15 mi (1,104.24 km) |
