| Knokke-Heist to Olympia Heights (Florida) | 4,583.20 mi (7,375.95 km) |
| Knokke-Heist to Omaha (Nebraska) | 4,420.10 mi (7,113.47 km) |
| Knokke-Heist to On Top of the World Designated Place (Florida) | 4,493.92 mi (7,232.27 km) |
| Knokke-Heist to Onalaska (Wisconsin) | 4,117.79 mi (6,626.94 km) |
| Knokke-Heist to Oneida (New York) | 3,567.03 mi (5,740.58 km) |
| Knokke-Heist to Oneonta (New York) | 3,570.27 mi (5,745.79 km) |
| Knokke-Heist to Ontario (California) | 5,536.79 mi (8,910.60 km) |
| Knokke-Heist to Ontario (Oregon) | 4,944.21 mi (7,956.93 km) |
| Knokke-Heist to Opa-locka (Florida) | 4,570.75 mi (7,355.91 km) |
| Knokke-Heist to Opelika (Alabama) | 4,442.60 mi (7,149.67 km) |
| Knokke-Heist to Opelousas (Louisiana) | 4,818.58 mi (7,754.75 km) |
| Knokke-Heist to Orange (California) | 5,557.16 mi (8,943.38 km) |
| Knokke-Heist to Orange (Texas) | 4,905.52 mi (7,894.67 km) |
| Knokke-Heist to Orange City (Florida) | 4,461.00 mi (7,179.29 km) |
| Knokke-Heist to Orangeburg (South Carolina) | 4,218.46 mi (6,788.95 km) |
