| Prospect Heights to Oerlinghausen | 4,256.19 mi (6,849.67 km) |
| Prospect Heights to Oestrich-Winkel | 4,306.61 mi (6,930.83 km) |
| Prospect Heights to Offenburg | 4,363.17 mi (7,021.84 km) |
| Prospect Heights to Oftersheim | 4,352.55 mi (7,004.75 km) |
| Prospect Heights to Ohrdruf | 4,374.00 mi (7,039.27 km) |
| Prospect Heights to Ohringen | 4,393.23 mi (7,070.22 km) |
| Prospect Heights to Olbernhau | 4,472.90 mi (7,198.44 km) |
| Prospect Heights to Olching | 4,500.79 mi (7,243.32 km) |
| Prospect Heights to Oldenburg | 4,196.26 mi (6,753.23 km) |
| Prospect Heights to Oldenburg in Holstein | 4,244.66 mi (6,831.13 km) |
| Prospect Heights to Olfen | 4,219.46 mi (6,790.56 km) |
| Prospect Heights to Olpe | 4,261.93 mi (6,858.92 km) |
| Prospect Heights to Olsberg | 4,272.92 mi (6,876.60 km) |
| Prospect Heights to Oranienburg | 4,384.79 mi (7,056.64 km) |
| Prospect Heights to Ortenberg | 4,331.74 mi (6,971.27 km) |
