| Effingham to Olympia Heights (Florida) | 1,041.02 mi (1,675.36 km) |
| Effingham to Omaha (Nebraska) | 422.54 mi (680.00 km) |
| Effingham to On Top of the World Designated Place (Florida) | 778.71 mi (1,253.21 km) |
| Effingham to Onalaska (Wisconsin) | 356.90 mi (574.38 km) |
| Effingham to Oneida (New York) | 723.65 mi (1,164.59 km) |
| Effingham to Oneonta (New York) | 741.11 mi (1,192.70 km) |
| Effingham to Ontario (California) | 1,642.43 mi (2,643.23 km) |
| Effingham to Ontario (Oregon) | 1,499.84 mi (2,413.75 km) |
| Effingham to Opa-locka (Florida) | 1,032.30 mi (1,661.32 km) |
| Effingham to Opelika (Alabama) | 480.27 mi (772.91 km) |
| Effingham to Opelousas (Louisiana) | 626.58 mi (1,008.39 km) |
| Effingham to Orange (California) | 1,659.80 mi (2,671.19 km) |
| Effingham to Orange (Texas) | 688.33 mi (1,107.75 km) |
| Effingham to Orange City (Florida) | 816.76 mi (1,314.44 km) |
| Effingham to Orangeburg (South Carolina) | 577.71 mi (929.74 km) |
