| Grays to Olympia Heights (Florida) | 4,456.37 mi (7,171.84 km) |
| Grays to Omaha (Nebraska) | 4,308.68 mi (6,934.15 km) |
| Grays to On Top of the World Designated Place (Florida) | 4,368.45 mi (7,030.34 km) |
| Grays to Onalaska (Wisconsin) | 4,005.57 mi (6,446.34 km) |
| Grays to Oneida (New York) | 3,446.10 mi (5,545.96 km) |
| Grays to Oneonta (New York) | 3,448.65 mi (5,550.07 km) |
| Grays to Ontario (California) | 5,436.95 mi (8,749.92 km) |
| Grays to Ontario (Oregon) | 4,852.35 mi (7,809.10 km) |
| Grays to Opa-locka (Florida) | 4,443.94 mi (7,151.83 km) |
| Grays to Opelika (Alabama) | 4,319.63 mi (6,951.78 km) |
| Grays to Opelousas (Louisiana) | 4,697.58 mi (7,560.02 km) |
| Grays to Orange (California) | 5,457.34 mi (8,782.75 km) |
| Grays to Orange (Texas) | 4,785.16 mi (7,700.97 km) |
| Grays to Orange City (Florida) | 4,335.20 mi (6,976.82 km) |
| Grays to Orangeburg (South Carolina) | 4,094.16 mi (6,588.91 km) |
