| California to Orbetello | 4,408.74 mi (7,095.18 km) |
| California to Oria | 4,762.53 mi (7,664.55 km) |
| California to Oristano | 4,374.39 mi (7,039.90 km) |
| California to Orta Nova | 4,647.04 mi (7,478.70 km) |
| California to Orte | 4,460.17 mi (7,177.95 km) |
| California to Ortona | 4,552.81 mi (7,327.04 km) |
| California to Orvieto | 4,439.18 mi (7,144.16 km) |
| California to Orzinuovi | 4,256.26 mi (6,849.79 km) |
| California to Osimo | 4,473.29 mi (7,199.06 km) |
| California to Ospitaletto | 4,257.42 mi (6,851.65 km) |
| California to Ostuni | 4,751.56 mi (7,646.90 km) |
| California to Ottaviano | 4,609.65 mi (7,418.52 km) |
| California to Ovada | 4,224.01 mi (6,797.88 km) |
| California to Ozieri | 4,370.74 mi (7,034.02 km) |
| California to Paceco | 4,625.01 mi (7,443.24 km) |
