| Glen Ellyn to Oerlinghausen | 4,272.84 mi (6,876.47 km) |
| Glen Ellyn to Oestrich-Winkel | 4,323.02 mi (6,957.23 km) |
| Glen Ellyn to Offenburg | 4,379.39 mi (7,047.94 km) |
| Glen Ellyn to Oftersheim | 4,368.91 mi (7,031.09 km) |
| Glen Ellyn to Ohrdruf | 4,390.62 mi (7,066.02 km) |
| Glen Ellyn to Ohringen | 4,409.62 mi (7,096.60 km) |
| Glen Ellyn to Olbernhau | 4,489.63 mi (7,225.35 km) |
| Glen Ellyn to Olching | 4,517.16 mi (7,269.67 km) |
| Glen Ellyn to Oldenburg | 4,213.02 mi (6,780.20 km) |
| Glen Ellyn to Oldenburg in Holstein | 4,261.63 mi (6,858.43 km) |
| Glen Ellyn to Olfen | 4,236.03 mi (6,817.22 km) |
| Glen Ellyn to Olpe | 4,278.44 mi (6,885.49 km) |
| Glen Ellyn to Olsberg | 4,289.50 mi (6,903.28 km) |
| Glen Ellyn to Oranienburg | 4,401.70 mi (7,083.86 km) |
| Glen Ellyn to Ortenberg | 4,348.24 mi (6,997.82 km) |
