| Galveston to Orbetello | 5,617.91 mi (9,041.15 km) |
| Galveston to Oria | 5,968.20 mi (9,604.89 km) |
| Galveston to Oristano | 5,592.70 mi (9,000.58 km) |
| Galveston to Orta Nova | 5,853.18 mi (9,419.78 km) |
| Galveston to Orte | 5,667.67 mi (9,121.24 km) |
| Galveston to Ortona | 5,757.68 mi (9,266.09 km) |
| Galveston to Orvieto | 5,646.25 mi (9,086.76 km) |
| Galveston to Orzinuovi | 5,457.02 mi (8,782.22 km) |
| Galveston to Osimo | 5,675.69 mi (9,134.13 km) |
| Galveston to Ospitaletto | 5,457.35 mi (8,782.76 km) |
| Galveston to Ostuni | 5,956.58 mi (9,586.19 km) |
| Galveston to Ottaviano | 5,819.08 mi (9,364.90 km) |
| Galveston to Ovada | 5,429.43 mi (8,737.82 km) |
| Galveston to Ozieri | 5,587.28 mi (8,991.86 km) |
| Galveston to Paceco | 5,843.44 mi (9,404.11 km) |
