| Gurnee to Orbetello | 4,726.28 mi (7,606.22 km) |
| Gurnee to Oria | 5,066.59 mi (8,153.89 km) |
| Gurnee to Oristano | 4,727.01 mi (7,607.39 km) |
| Gurnee to Orta Nova | 4,953.38 mi (7,971.70 km) |
| Gurnee to Orte | 4,772.13 mi (7,680.00 km) |
| Gurnee to Ortona | 4,856.34 mi (7,815.52 km) |
| Gurnee to Orvieto | 4,750.03 mi (7,644.43 km) |
| Gurnee to Orzinuovi | 4,551.21 mi (7,324.47 km) |
| Gurnee to Osimo | 4,770.71 mi (7,677.72 km) |
| Gurnee to Ospitaletto | 4,550.24 mi (7,322.90 km) |
| Gurnee to Ostuni | 5,053.86 mi (8,133.40 km) |
| Gurnee to Ottaviano | 4,926.24 mi (7,928.02 km) |
| Gurnee to Ovada | 4,531.94 mi (7,293.46 km) |
| Gurnee to Ozieri | 4,715.35 mi (7,588.63 km) |
| Gurnee to Paceco | 4,975.85 mi (8,007.86 km) |
