| Williamstown to Orbetello | 4,287.43 mi (6,899.95 km) |
| Williamstown to Oria | 4,640.69 mi (7,468.46 km) |
| Williamstown to Oristano | 4,255.42 mi (6,848.44 km) |
| Williamstown to Orta Nova | 4,525.25 mi (7,282.69 km) |
| Williamstown to Orte | 4,338.57 mi (6,982.25 km) |
| Williamstown to Ortona | 4,430.80 mi (7,130.69 km) |
| Williamstown to Orvieto | 4,317.50 mi (6,948.34 km) |
| Williamstown to Orzinuovi | 4,133.61 mi (6,652.41 km) |
| Williamstown to Osimo | 4,350.90 mi (7,002.10 km) |
| Williamstown to Ospitaletto | 4,134.66 mi (6,654.10 km) |
| Williamstown to Ostuni | 4,629.62 mi (7,450.65 km) |
| Williamstown to Ottaviano | 4,488.43 mi (7,223.43 km) |
| Williamstown to Ovada | 4,102.02 mi (6,601.56 km) |
| Williamstown to Ozieri | 4,251.18 mi (6,841.61 km) |
| Williamstown to Paceco | 4,506.12 mi (7,251.90 km) |
