| East Chicago to Oswego (Illinois) | 45.63 mi (73.44 km) |
| East Chicago to Oswego (New York) | 570.88 mi (918.74 km) |
| East Chicago to Otsego (Minnesota) | 397.48 mi (639.69 km) |
| East Chicago to Ottawa (Illinois) | 73.78 mi (118.73 km) |
| East Chicago to Ottawa (Kansas) | 462.94 mi (745.03 km) |
| East Chicago to Ottumwa (Iowa) | 261.13 mi (420.24 km) |
| East Chicago to Overland (Missouri) | 255.36 mi (410.96 km) |
| East Chicago to Overland Park (Kansas) | 426.13 mi (685.79 km) |
| East Chicago to Overlea (Maryland) | 595.35 mi (958.13 km) |
| East Chicago to Oviedo (Florida) | 964.04 mi (1,551.48 km) |
| East Chicago to Owasso (Oklahoma) | 582.25 mi (937.05 km) |
| East Chicago to Owatonna (Minnesota) | 337.66 mi (543.41 km) |
| East Chicago to Owensboro (Kentucky) | 269.33 mi (433.44 km) |
| East Chicago to Owings Mills (Maryland) | 580.46 mi (934.16 km) |
| East Chicago to Owosso (Michigan) | 191.64 mi (308.42 km) |
