| Rockville to Orbetello | 4,407.07 mi (7,092.49 km) |
| Rockville to Oria | 4,759.79 mi (7,660.14 km) |
| Rockville to Oristano | 4,376.74 mi (7,043.69 km) |
| Rockville to Orta Nova | 4,644.42 mi (7,474.47 km) |
| Rockville to Orte | 4,457.94 mi (7,174.35 km) |
| Rockville to Ortona | 4,549.75 mi (7,322.11 km) |
| Rockville to Orvieto | 4,436.79 mi (7,140.32 km) |
| Rockville to Orzinuovi | 4,251.84 mi (6,842.68 km) |
| Rockville to Osimo | 4,469.44 mi (7,192.86 km) |
| Rockville to Ospitaletto | 4,252.76 mi (6,844.16 km) |
| Rockville to Ostuni | 4,748.61 mi (7,642.15 km) |
| Rockville to Ottaviano | 4,608.14 mi (7,416.08 km) |
| Rockville to Ovada | 4,221.00 mi (6,793.05 km) |
| Rockville to Ozieri | 4,372.15 mi (7,036.29 km) |
| Rockville to Paceco | 4,627.47 mi (7,447.19 km) |
