| Union to Oerlinghausen | 4,551.62 mi (7,325.13 km) |
| Union to Oestrich-Winkel | 4,599.89 mi (7,402.80 km) |
| Union to Offenburg | 4,654.72 mi (7,491.05 km) |
| Union to Oftersheim | 4,645.42 mi (7,476.09 km) |
| Union to Ohrdruf | 4,669.18 mi (7,514.32 km) |
| Union to Ohringen | 4,686.35 mi (7,541.95 km) |
| Union to Olbernhau | 4,768.91 mi (7,674.82 km) |
| Union to Olching | 4,793.74 mi (7,714.78 km) |
| Union to Oldenburg | 4,492.55 mi (7,230.06 km) |
| Union to Oldenburg in Holstein | 4,542.51 mi (7,310.46 km) |
| Union to Olfen | 4,514.20 mi (7,264.91 km) |
| Union to Olpe | 4,556.17 mi (7,332.45 km) |
| Union to Olsberg | 4,567.73 mi (7,351.05 km) |
| Union to Oranienburg | 4,682.26 mi (7,535.36 km) |
| Union to Ortenberg | 4,625.83 mi (7,444.55 km) |
