| Rockford to Oerlinghausen | 4,288.81 mi (6,902.17 km) |
| Rockford to Oestrich-Winkel | 4,341.04 mi (6,986.22 km) |
| Rockford to Offenburg | 4,398.80 mi (7,079.18 km) |
| Rockford to Oftersheim | 4,387.26 mi (7,060.62 km) |
| Rockford to Ohrdruf | 4,406.83 mi (7,092.10 km) |
| Rockford to Ohringen | 4,427.76 mi (7,125.78 km) |
| Rockford to Olbernhau | 4,504.93 mi (7,249.98 km) |
| Rockford to Olching | 4,535.42 mi (7,299.05 km) |
| Rockford to Oldenburg | 4,228.06 mi (6,804.41 km) |
| Rockford to Oldenburg in Holstein | 4,274.62 mi (6,879.34 km) |
| Rockford to Olfen | 4,252.71 mi (6,844.07 km) |
| Rockford to Olpe | 4,295.60 mi (6,913.11 km) |
| Rockford to Olsberg | 4,306.10 mi (6,930.00 km) |
| Rockford to Oranienburg | 4,415.22 mi (7,105.60 km) |
| Rockford to Ortenberg | 4,365.53 mi (7,025.64 km) |
