| Romeoville to Oskaloosa (Iowa) | 236.25 mi (380.21 km) |
| Romeoville to Oswego (Illinois) | 12.77 mi (20.55 km) |
| Romeoville to Oswego (New York) | 603.18 mi (970.73 km) |
| Romeoville to Otsego (Minnesota) | 373.64 mi (601.31 km) |
| Romeoville to Ottawa (Illinois) | 42.16 mi (67.85 km) |
| Romeoville to Ottawa (Kansas) | 432.43 mi (695.93 km) |
| Romeoville to Ottumwa (Iowa) | 228.03 mi (366.97 km) |
| Romeoville to Overland (Missouri) | 235.53 mi (379.05 km) |
| Romeoville to Overland Park (Kansas) | 395.57 mi (636.61 km) |
| Romeoville to Overlea (Maryland) | 627.83 mi (1,010.40 km) |
| Romeoville to Oviedo (Florida) | 976.92 mi (1,572.20 km) |
| Romeoville to Owasso (Oklahoma) | 555.34 mi (893.73 km) |
| Romeoville to Owatonna (Minnesota) | 310.42 mi (499.57 km) |
| Romeoville to Owensboro (Kentucky) | 272.73 mi (438.92 km) |
| Romeoville to Owings Mills (Maryland) | 612.92 mi (986.40 km) |
