| Pittsburgh to Oerlinghausen | 4,044.21 mi (6,508.52 km) |
| Pittsburgh to Oestrich-Winkel | 4,080.52 mi (6,566.96 km) |
| Pittsburgh to Offenburg | 4,127.45 mi (6,642.48 km) |
| Pittsburgh to Oftersheim | 4,123.95 mi (6,636.86 km) |
| Pittsburgh to Ohrdruf | 4,159.68 mi (6,694.35 km) |
| Pittsburgh to Ohringen | 4,165.83 mi (6,704.25 km) |
| Pittsburgh to Olbernhau | 4,264.08 mi (6,862.37 km) |
| Pittsburgh to Olching | 4,271.97 mi (6,875.08 km) |
| Pittsburgh to Oldenburg | 3,991.01 mi (6,422.91 km) |
| Pittsburgh to Oldenburg in Holstein | 4,053.12 mi (6,522.86 km) |
| Pittsburgh to Olfen | 4,002.91 mi (6,442.07 km) |
| Pittsburgh to Olpe | 4,041.89 mi (6,504.80 km) |
| Pittsburgh to Olsberg | 4,056.53 mi (6,528.36 km) |
| Pittsburgh to Oranienburg | 4,188.73 mi (6,741.11 km) |
| Pittsburgh to Ortenberg | 4,110.40 mi (6,615.06 km) |
