| Glenn Dale to Orbetello | 4,395.49 mi (7,073.85 km) |
| Glenn Dale to Oria | 4,748.49 mi (7,641.95 km) |
| Glenn Dale to Oristano | 4,364.16 mi (7,023.44 km) |
| Glenn Dale to Orta Nova | 4,633.09 mi (7,456.23 km) |
| Glenn Dale to Orte | 4,446.50 mi (7,155.95 km) |
| Glenn Dale to Ortona | 4,538.52 mi (7,304.05 km) |
| Glenn Dale to Orvieto | 4,425.39 mi (7,121.98 km) |
| Glenn Dale to Orzinuovi | 4,240.96 mi (6,825.17 km) |
| Glenn Dale to Osimo | 4,458.42 mi (7,175.13 km) |
| Glenn Dale to Ospitaletto | 4,241.94 mi (6,826.75 km) |
| Glenn Dale to Ostuni | 4,737.37 mi (7,624.06 km) |
| Glenn Dale to Ottaviano | 4,596.52 mi (7,397.39 km) |
| Glenn Dale to Ovada | 4,209.75 mi (6,774.95 km) |
| Glenn Dale to Ozieri | 4,359.80 mi (7,016.42 km) |
| Glenn Dale to Paceco | 4,614.87 mi (7,426.92 km) |
