| Duffel to Olympia Heights (Florida) | 4,638.78 mi (7,465.40 km) |
| Duffel to Omaha (Nebraska) | 4,473.32 mi (7,199.12 km) |
| Duffel to On Top of the World Designated Place (Florida) | 4,549.69 mi (7,322.01 km) |
| Duffel to Onalaska (Wisconsin) | 4,171.23 mi (6,712.95 km) |
| Duffel to Oneida (New York) | 3,622.40 mi (5,829.68 km) |
| Duffel to Oneonta (New York) | 3,625.74 mi (5,835.06 km) |
| Duffel to Ontario (California) | 5,586.54 mi (8,990.67 km) |
| Duffel to Ontario (Oregon) | 4,991.44 mi (8,032.95 km) |
| Duffel to Opa-locka (Florida) | 4,626.34 mi (7,445.37 km) |
| Duffel to Opelika (Alabama) | 4,498.23 mi (7,239.21 km) |
| Duffel to Opelousas (Louisiana) | 4,873.94 mi (7,843.84 km) |
| Duffel to Orange (California) | 5,606.90 mi (9,023.44 km) |
| Duffel to Orange (Texas) | 4,960.77 mi (7,983.58 km) |
| Duffel to Orange City (Florida) | 4,516.75 mi (7,269.01 km) |
| Duffel to Orangeburg (South Carolina) | 4,274.20 mi (6,878.67 km) |
