| Delaware to Oerlinghausen | 4,168.36 mi (6,708.33 km) |
| Delaware to Oestrich-Winkel | 4,208.73 mi (6,773.30 km) |
| Delaware to Offenburg | 4,258.39 mi (6,853.21 km) |
| Delaware to Oftersheim | 4,252.91 mi (6,844.40 km) |
| Delaware to Ohrdruf | 4,284.64 mi (6,895.46 km) |
| Delaware to Ohringen | 4,294.50 mi (6,911.33 km) |
| Delaware to Olbernhau | 4,387.58 mi (7,061.13 km) |
| Delaware to Olching | 4,401.15 mi (7,082.97 km) |
| Delaware to Oldenburg | 4,113.15 mi (6,619.47 km) |
| Delaware to Oldenburg in Holstein | 4,171.31 mi (6,713.08 km) |
| Delaware to Olfen | 4,128.33 mi (6,643.90 km) |
| Delaware to Olpe | 4,168.35 mi (6,708.31 km) |
| Delaware to Olsberg | 4,181.96 mi (6,730.22 km) |
| Delaware to Oranienburg | 4,308.43 mi (6,933.74 km) |
| Delaware to Ortenberg | 4,237.31 mi (6,819.29 km) |
