| Hackettstown to Oerlinghausen | 3,826.79 mi (6,158.63 km) |
| Hackettstown to Oestrich-Winkel | 3,856.69 mi (6,206.74 km) |
| Hackettstown to Offenburg | 3,899.30 mi (6,275.32 km) |
| Hackettstown to Oftersheim | 3,898.88 mi (6,274.64 km) |
| Hackettstown to Ohrdruf | 3,940.77 mi (6,342.06 km) |
| Hackettstown to Ohringen | 3,941.13 mi (6,342.64 km) |
| Hackettstown to Olbernhau | 4,047.26 mi (6,513.44 km) |
| Hackettstown to Olching | 4,046.32 mi (6,511.92 km) |
| Hackettstown to Oldenburg | 3,776.87 mi (6,078.28 km) |
| Hackettstown to Oldenburg in Holstein | 3,845.09 mi (6,188.08 km) |
| Hackettstown to Olfen | 3,783.60 mi (6,089.12 km) |
| Hackettstown to Olpe | 3,820.87 mi (6,149.10 km) |
| Hackettstown to Olsberg | 3,837.09 mi (6,175.19 km) |
| Hackettstown to Oranienburg | 3,978.03 mi (6,402.02 km) |
| Hackettstown to Ortenberg | 3,888.56 mi (6,258.03 km) |
