| Grass Valley to Orbetello | 6,051.25 mi (9,738.54 km) |
| Grass Valley to Oria | 6,344.19 mi (10,209.99 km) |
| Grass Valley to Oristano | 6,113.38 mi (9,838.53 km) |
| Grass Valley to Orta Nova | 6,242.91 mi (10,046.99 km) |
| Grass Valley to Orte | 6,084.06 mi (9,791.35 km) |
| Grass Valley to Ortona | 6,147.25 mi (9,893.05 km) |
| Grass Valley to Orvieto | 6,061.43 mi (9,754.93 km) |
| Grass Valley to Orzinuovi | 5,847.74 mi (9,411.02 km) |
| Grass Valley to Osimo | 6,056.34 mi (9,746.73 km) |
| Grass Valley to Ospitaletto | 5,843.03 mi (9,403.44 km) |
| Grass Valley to Ostuni | 6,329.00 mi (10,185.55 km) |
| Grass Valley to Ottaviano | 6,236.45 mi (10,036.60 km) |
| Grass Valley to Ovada | 5,852.79 mi (9,419.15 km) |
| Grass Valley to Ozieri | 6,088.58 mi (9,798.63 km) |
| Grass Valley to Paceco | 6,344.81 mi (10,210.99 km) |
