| Havre de Grace to Orbetello | 4,343.03 mi (6,989.43 km) |
| Havre de Grace to Oria | 4,695.84 mi (7,557.23 km) |
| Havre de Grace to Oristano | 4,312.52 mi (6,940.33 km) |
| Havre de Grace to Orta Nova | 4,580.46 mi (7,371.54 km) |
| Havre de Grace to Orte | 4,393.94 mi (7,071.37 km) |
| Havre de Grace to Ortona | 4,485.83 mi (7,219.25 km) |
| Havre de Grace to Orvieto | 4,372.81 mi (7,037.36 km) |
| Havre de Grace to Orzinuovi | 4,188.07 mi (6,740.04 km) |
| Havre de Grace to Osimo | 4,405.60 mi (7,090.13 km) |
| Havre de Grace to Ospitaletto | 4,189.02 mi (6,741.57 km) |
| Havre de Grace to Ostuni | 4,684.69 mi (7,539.28 km) |
| Havre de Grace to Ottaviano | 4,544.09 mi (7,313.00 km) |
| Havre de Grace to Ovada | 4,157.08 mi (6,690.17 km) |
| Havre de Grace to Ozieri | 4,307.94 mi (6,932.97 km) |
| Havre de Grace to Paceco | 4,563.24 mi (7,343.83 km) |
