| Flagstaff to Oerlinghausen | 5,421.51 mi (8,725.07 km) |
| Flagstaff to Oestrich-Winkel | 5,494.69 mi (8,842.86 km) |
| Flagstaff to Offenburg | 5,565.87 mi (8,957.40 km) |
| Flagstaff to Oftersheim | 5,543.70 mi (8,921.72 km) |
| Flagstaff to Ohrdruf | 5,540.14 mi (8,915.99 km) |
| Flagstaff to Ohringen | 5,581.37 mi (8,982.35 km) |
| Flagstaff to Olbernhau | 5,626.56 mi (9,055.08 km) |
| Flagstaff to Olching | 5,688.71 mi (9,155.09 km) |
| Flagstaff to Oldenburg | 5,351.58 mi (8,612.54 km) |
| Flagstaff to Oldenburg in Holstein | 5,373.94 mi (8,648.53 km) |
| Flagstaff to Olfen | 5,393.65 mi (8,680.24 km) |
| Flagstaff to Olpe | 5,440.94 mi (8,756.34 km) |
| Flagstaff to Olsberg | 5,445.39 mi (8,763.51 km) |
| Flagstaff to Oranienburg | 5,517.91 mi (8,880.21 km) |
| Flagstaff to Ortenberg | 5,511.14 mi (8,869.32 km) |
