| Fort Thomas to Olympia Heights (Florida) | 953.19 mi (1,534.02 km) |
| Fort Thomas to Omaha (Nebraska) | 630.24 mi (1,014.27 km) |
| Fort Thomas to On Top of the World Designated Place (Florida) | 700.14 mi (1,126.76 km) |
| Fort Thomas to Onalaska (Wisconsin) | 482.02 mi (775.73 km) |
| Fort Thomas to Oneida (New York) | 534.21 mi (859.72 km) |
| Fort Thomas to Oneonta (New York) | 543.25 mi (874.27 km) |
| Fort Thomas to Ontario (California) | 1,862.01 mi (2,996.61 km) |
| Fort Thomas to Ontario (Oregon) | 1,704.42 mi (2,743.01 km) |
| Fort Thomas to Opa-locka (Florida) | 942.63 mi (1,517.02 km) |
| Fort Thomas to Opelika (Alabama) | 446.51 mi (718.59 km) |
| Fort Thomas to Opelousas (Louisiana) | 731.99 mi (1,178.03 km) |
| Fort Thomas to Orange (California) | 1,879.31 mi (3,024.46 km) |
| Fort Thomas to Orange (Texas) | 813.47 mi (1,309.16 km) |
| Fort Thomas to Orange City (Florida) | 723.87 mi (1,164.96 km) |
| Fort Thomas to Orangeburg (South Carolina) | 434.51 mi (699.28 km) |
