| Rockford to Olympia (Washington) | 1,681.70 mi (2,706.44 km) |
| Rockford to Olympia Heights (Florida) | 1,245.34 mi (2,004.18 km) |
| Rockford to Omaha (Nebraska) | 366.61 mi (590.01 km) |
| Rockford to On Top of the World Designated Place (Florida) | 984.37 mi (1,584.19 km) |
| Rockford to Onalaska (Wisconsin) | 156.09 mi (251.20 km) |
| Rockford to Oneida (New York) | 682.47 mi (1,098.32 km) |
| Rockford to Oneonta (New York) | 713.98 mi (1,149.04 km) |
| Rockford to Ontario (California) | 1,642.17 mi (2,642.82 km) |
| Rockford to Ontario (Oregon) | 1,405.68 mi (2,262.23 km) |
| Rockford to Opa-locka (Florida) | 1,235.95 mi (1,989.06 km) |
| Rockford to Opelika (Alabama) | 693.14 mi (1,115.49 km) |
| Rockford to Opelousas (Louisiana) | 827.80 mi (1,332.21 km) |
| Rockford to Orange (California) | 1,660.84 mi (2,672.87 km) |
| Rockford to Orange (Texas) | 878.14 mi (1,413.23 km) |
| Rockford to Orange City (Florida) | 1,017.92 mi (1,638.19 km) |
