| Pittsburgh to Orbetello | 4,476.01 mi (7,203.45 km) |
| Pittsburgh to Oria | 4,825.55 mi (7,765.97 km) |
| Pittsburgh to Oristano | 4,455.62 mi (7,170.62 km) |
| Pittsburgh to Orta Nova | 4,710.62 mi (7,581.01 km) |
| Pittsburgh to Orte | 4,525.39 mi (7,282.91 km) |
| Pittsburgh to Ortona | 4,614.99 mi (7,427.10 km) |
| Pittsburgh to Orvieto | 4,503.89 mi (7,248.31 km) |
| Pittsburgh to Orzinuovi | 4,314.10 mi (6,942.87 km) |
| Pittsburgh to Osimo | 4,532.81 mi (7,294.85 km) |
| Pittsburgh to Ospitaletto | 4,314.42 mi (6,943.38 km) |
| Pittsburgh to Ostuni | 4,813.86 mi (7,747.16 km) |
| Pittsburgh to Ottaviano | 4,677.17 mi (7,527.17 km) |
| Pittsburgh to Ovada | 4,286.87 mi (6,899.06 km) |
| Pittsburgh to Ozieri | 4,448.73 mi (7,159.53 km) |
| Pittsburgh to Paceco | 4,706.24 mi (7,573.96 km) |
