| Effingham to Oswego (Illinois) | 177.44 mi (285.56 km) |
| Effingham to Oswego (New York) | 692.62 mi (1,114.67 km) |
| Effingham to Otsego (Minnesota) | 497.38 mi (800.46 km) |
| Effingham to Ottawa (Illinois) | 155.10 mi (249.62 km) |
| Effingham to Ottawa (Kansas) | 362.86 mi (583.96 km) |
| Effingham to Ottumwa (Iowa) | 242.94 mi (390.97 km) |
| Effingham to Overland (Missouri) | 102.04 mi (164.21 km) |
| Effingham to Overland Park (Kansas) | 329.80 mi (530.75 km) |
| Effingham to Overlea (Maryland) | 643.67 mi (1,035.88 km) |
| Effingham to Oviedo (Florida) | 836.48 mi (1,346.19 km) |
| Effingham to Owasso (Oklahoma) | 443.31 mi (713.43 km) |
| Effingham to Owatonna (Minnesota) | 419.86 mi (675.70 km) |
| Effingham to Owensboro (Kentucky) | 122.02 mi (196.37 km) |
| Effingham to Owings Mills (Maryland) | 628.93 mi (1,012.17 km) |
| Effingham to Owosso (Michigan) | 351.51 mi (565.70 km) |
