| Longford to Olympia Heights (Florida) | 4,100.41 mi (6,598.97 km) |
| Longford to Omaha (Nebraska) | 3,935.38 mi (6,333.39 km) |
| Longford to On Top of the World Designated Place (Florida) | 4,005.10 mi (6,445.58 km) |
| Longford to Onalaska (Wisconsin) | 3,631.91 mi (5,844.99 km) |
| Longford to Oneida (New York) | 3,073.40 mi (4,946.17 km) |
| Longford to Oneonta (New York) | 3,076.71 mi (4,951.49 km) |
| Longford to Ontario (California) | 5,073.63 mi (8,165.21 km) |
| Longford to Ontario (Oregon) | 4,500.02 mi (7,242.08 km) |
| Longford to Opa-locka (Florida) | 4,087.83 mi (6,578.73 km) |
| Longford to Opelika (Alabama) | 3,949.65 mi (6,356.35 km) |
| Longford to Opelousas (Louisiana) | 4,324.95 mi (6,960.34 km) |
| Longford to Orange (California) | 5,094.04 mi (8,198.07 km) |
| Longford to Orange (Texas) | 4,411.96 mi (7,100.37 km) |
| Longford to Orange City (Florida) | 3,973.27 mi (6,394.36 km) |
| Longford to Orangeburg (South Carolina) | 3,727.09 mi (5,998.17 km) |
