| Willoughby to Olympia (Washington) | 2,058.69 mi (3,313.15 km) |
| Willoughby to Olympia Heights (Florida) | 1,101.79 mi (1,773.16 km) |
| Willoughby to Omaha (Nebraska) | 757.91 mi (1,219.73 km) |
| Willoughby to On Top of the World Designated Place (Florida) | 867.83 mi (1,396.64 km) |
| Willoughby to Onalaska (Wisconsin) | 520.25 mi (837.26 km) |
| Willoughby to Oneida (New York) | 309.50 mi (498.09 km) |
| Willoughby to Oneonta (New York) | 330.06 mi (531.17 km) |
| Willoughby to Ontario (California) | 2,027.60 mi (3,263.10 km) |
| Willoughby to Ontario (Oregon) | 1,795.54 mi (2,889.64 km) |
| Willoughby to Opa-locka (Florida) | 1,089.94 mi (1,754.09 km) |
| Willoughby to Opelika (Alabama) | 657.92 mi (1,058.82 km) |
| Willoughby to Opelousas (Louisiana) | 970.72 mi (1,562.22 km) |
| Willoughby to Orange (California) | 2,045.82 mi (3,292.43 km) |
| Willoughby to Orange (Texas) | 1,052.26 mi (1,693.45 km) |
| Willoughby to Orange City (Florida) | 878.28 mi (1,413.45 km) |
