| Chicago Heights to Olivares | 4,187.70 mi (6,739.45 km) |
| Chicago Heights to Olivenza | 4,097.94 mi (6,595.00 km) |
| Chicago Heights to Olot | 4,397.87 mi (7,077.69 km) |
| Chicago Heights to Onate | 4,155.15 mi (6,687.06 km) |
| Chicago Heights to Onda | 4,361.69 mi (7,019.46 km) |
| Chicago Heights to Onteniente | 4,389.46 mi (7,064.15 km) |
| Chicago Heights to Orihuela | 4,402.15 mi (7,084.58 km) |
| Chicago Heights to Osuna | 4,243.33 mi (6,828.98 km) |
| Chicago Heights to Ourense | 3,938.27 mi (6,338.03 km) |
| Chicago Heights to Oviedo | 3,994.02 mi (6,427.76 km) |
| Chicago Heights to Paiporta | 4,374.98 mi (7,040.85 km) |
| Chicago Heights to Pajara | 4,138.72 mi (6,660.62 km) |
| Chicago Heights to Palafolls | 4,428.64 mi (7,127.21 km) |
| Chicago Heights to Palafrugell | 4,436.81 mi (7,140.35 km) |
| Chicago Heights to Palamos | 4,438.09 mi (7,142.42 km) |
