| Rockford to Oskaloosa (Iowa) | 196.01 mi (315.45 km) |
| Rockford to Oswego (Illinois) | 54.58 mi (87.84 km) |
| Rockford to Oswego (New York) | 641.02 mi (1,031.63 km) |
| Rockford to Otsego (Minnesota) | 307.86 mi (495.45 km) |
| Rockford to Ottawa (Illinois) | 63.66 mi (102.45 km) |
| Rockford to Ottawa (Kansas) | 412.44 mi (663.76 km) |
| Rockford to Ottumwa (Iowa) | 193.23 mi (310.98 km) |
| Rockford to Overland (Missouri) | 255.54 mi (411.26 km) |
| Rockford to Overland Park (Kansas) | 375.87 mi (604.90 km) |
| Rockford to Overlea (Maryland) | 685.17 mi (1,102.68 km) |
| Rockford to Oviedo (Florida) | 1,037.91 mi (1,670.36 km) |
| Rockford to Owasso (Oklahoma) | 548.49 mi (882.71 km) |
| Rockford to Owatonna (Minnesota) | 245.11 mi (394.47 km) |
| Rockford to Owensboro (Kentucky) | 327.66 mi (527.31 km) |
| Rockford to Owings Mills (Maryland) | 670.35 mi (1,078.83 km) |
