| Prospect Heights to Orbetello | 4,737.25 mi (7,623.86 km) |
| Prospect Heights to Oria | 5,077.99 mi (8,172.24 km) |
| Prospect Heights to Oristano | 4,737.06 mi (7,623.56 km) |
| Prospect Heights to Orta Nova | 4,964.70 mi (7,989.91 km) |
| Prospect Heights to Orte | 4,783.25 mi (7,697.90 km) |
| Prospect Heights to Ortona | 4,867.69 mi (7,833.79 km) |
| Prospect Heights to Orvieto | 4,761.17 mi (7,662.36 km) |
| Prospect Heights to Orzinuovi | 4,562.67 mi (7,342.91 km) |
| Prospect Heights to Osimo | 4,782.18 mi (7,696.18 km) |
| Prospect Heights to Ospitaletto | 4,561.75 mi (7,341.43 km) |
| Prospect Heights to Ostuni | 5,065.30 mi (8,151.82 km) |
| Prospect Heights to Ottaviano | 4,937.29 mi (7,945.81 km) |
| Prospect Heights to Ovada | 4,543.08 mi (7,311.39 km) |
| Prospect Heights to Ozieri | 4,725.62 mi (7,605.14 km) |
| Prospect Heights to Paceco | 4,986.03 mi (8,024.24 km) |
