| Barstow to Orbetello | 6,175.59 mi (9,938.66 km) |
| Barstow to Oria | 6,485.56 mi (10,437.51 km) |
| Barstow to Oristano | 6,218.39 mi (10,007.52 km) |
| Barstow to Orta Nova | 6,379.79 mi (10,267.28 km) |
| Barstow to Orte | 6,212.72 mi (9,998.40 km) |
| Barstow to Ortona | 6,282.83 mi (10,111.24 km) |
| Barstow to Orvieto | 6,190.04 mi (9,961.90 km) |
| Barstow to Orzinuovi | 5,978.81 mi (9,621.97 km) |
| Barstow to Osimo | 6,192.63 mi (9,966.07 km) |
| Barstow to Ospitaletto | 5,975.16 mi (9,616.10 km) |
| Barstow to Ostuni | 6,470.96 mi (10,414.00 km) |
| Barstow to Ottaviano | 6,367.02 mi (10,246.74 km) |
| Barstow to Ovada | 5,976.59 mi (9,618.39 km) |
| Barstow to Ozieri | 6,197.79 mi (9,974.37 km) |
| Barstow to Paceco | 6,457.57 mi (10,392.46 km) |
