| Mount Prospect to Orbetello | 4,739.39 mi (7,627.31 km) |
| Mount Prospect to Oria | 5,080.19 mi (8,175.78 km) |
| Mount Prospect to Oristano | 4,739.09 mi (7,626.83 km) |
| Mount Prospect to Orta Nova | 4,966.88 mi (7,993.42 km) |
| Mount Prospect to Orte | 4,785.41 mi (7,701.38 km) |
| Mount Prospect to Ortona | 4,869.88 mi (7,837.31 km) |
| Mount Prospect to Orvieto | 4,763.33 mi (7,665.84 km) |
| Mount Prospect to Orzinuovi | 4,564.88 mi (7,346.46 km) |
| Mount Prospect to Osimo | 4,784.39 mi (7,699.73 km) |
| Mount Prospect to Ospitaletto | 4,563.96 mi (7,344.99 km) |
| Mount Prospect to Ostuni | 5,067.50 mi (8,155.36 km) |
| Mount Prospect to Ottaviano | 4,939.45 mi (7,949.28 km) |
| Mount Prospect to Ovada | 4,545.25 mi (7,314.87 km) |
| Mount Prospect to Ozieri | 4,727.67 mi (7,608.46 km) |
| Mount Prospect to Paceco | 4,988.08 mi (8,027.53 km) |
