| Didcot to Olympia Heights (Florida) | 4,388.29 mi (7,062.27 km) |
| Didcot to Omaha (Nebraska) | 4,246.63 mi (6,834.30 km) |
| Didcot to On Top of the World Designated Place (Florida) | 4,300.68 mi (6,921.27 km) |
| Didcot to Onalaska (Wisconsin) | 3,943.19 mi (6,345.96 km) |
| Didcot to Oneida (New York) | 3,379.98 mi (5,439.55 km) |
| Didcot to Oneonta (New York) | 3,382.26 mi (5,443.21 km) |
| Didcot to Ontario (California) | 5,380.15 mi (8,658.52 km) |
| Didcot to Ontario (Oregon) | 4,799.49 mi (7,724.03 km) |
| Didcot to Opa-locka (Florida) | 4,375.86 mi (7,042.26 km) |
| Didcot to Opelika (Alabama) | 4,252.69 mi (6,844.05 km) |
| Didcot to Opelousas (Louisiana) | 4,631.38 mi (7,453.49 km) |
| Didcot to Orange (California) | 5,400.56 mi (8,691.36 km) |
| Didcot to Orange (Texas) | 4,719.21 mi (7,594.84 km) |
| Didcot to Orange City (Florida) | 4,267.33 mi (6,867.60 km) |
| Didcot to Orangeburg (South Carolina) | 4,026.75 mi (6,480.43 km) |
