| Herndon to Orbetello | 4,421.74 mi (7,116.11 km) |
| Herndon to Oria | 4,774.45 mi (7,683.73 km) |
| Herndon to Oristano | 4,391.43 mi (7,067.32 km) |
| Herndon to Orta Nova | 4,659.08 mi (7,498.06 km) |
| Herndon to Orte | 4,472.60 mi (7,197.96 km) |
| Herndon to Ortona | 4,564.40 mi (7,345.70 km) |
| Herndon to Orvieto | 4,451.46 mi (7,163.93 km) |
| Herndon to Orzinuovi | 4,266.48 mi (6,866.23 km) |
| Herndon to Osimo | 4,484.08 mi (7,216.43 km) |
| Herndon to Ospitaletto | 4,267.39 mi (6,867.71 km) |
| Herndon to Ostuni | 4,763.27 mi (7,665.75 km) |
| Herndon to Ottaviano | 4,622.81 mi (7,439.70 km) |
| Herndon to Ovada | 4,235.66 mi (6,816.64 km) |
| Herndon to Ozieri | 4,386.83 mi (7,059.93 km) |
| Herndon to Paceco | 4,642.15 mi (7,470.82 km) |
