| Boulder City to Orbetello | 6,050.84 mi (9,737.88 km) |
| Boulder City to Oria | 6,363.49 mi (10,241.05 km) |
| Boulder City to Oristano | 6,090.67 mi (9,801.99 km) |
| Boulder City to Orta Nova | 6,257.00 mi (10,069.67 km) |
| Boulder City to Orte | 6,088.64 mi (9,798.72 km) |
| Boulder City to Ortona | 6,159.88 mi (9,913.38 km) |
| Boulder City to Orvieto | 6,065.97 mi (9,762.24 km) |
| Boulder City to Orzinuovi | 5,855.33 mi (9,423.24 km) |
| Boulder City to Osimo | 6,069.88 mi (9,768.52 km) |
| Boulder City to Ospitaletto | 5,851.86 mi (9,417.67 km) |
| Boulder City to Ostuni | 6,349.00 mi (10,217.72 km) |
| Boulder City to Ottaviano | 6,243.15 mi (10,047.38 km) |
| Boulder City to Ovada | 5,851.89 mi (9,417.70 km) |
| Boulder City to Ozieri | 6,070.69 mi (9,769.83 km) |
| Boulder City to Paceco | 6,330.82 mi (10,188.47 km) |
