| Tucson to Orbetello | 6,110.72 mi (9,834.25 km) |
| Tucson to Oria | 6,437.15 mi (10,359.59 km) |
| Tucson to Oristano | 6,131.65 mi (9,867.93 km) |
| Tucson to Orta Nova | 6,327.22 mi (10,182.68 km) |
| Tucson to Orte | 6,152.35 mi (9,901.25 km) |
| Tucson to Ortona | 6,229.68 mi (10,025.70 km) |
| Tucson to Orvieto | 6,129.83 mi (9,865.01 km) |
| Tucson to Orzinuovi | 5,923.42 mi (9,532.82 km) |
| Tucson to Osimo | 6,141.14 mi (9,883.22 km) |
| Tucson to Ospitaletto | 5,921.01 mi (9,528.94 km) |
| Tucson to Ostuni | 6,423.35 mi (10,337.38 km) |
| Tucson to Ottaviano | 6,307.37 mi (10,150.74 km) |
| Tucson to Ovada | 5,912.98 mi (9,516.02 km) |
| Tucson to Ozieri | 6,115.85 mi (9,842.50 km) |
| Tucson to Paceco | 6,377.11 mi (10,262.97 km) |
