| Clay to Oerlinghausen | 4,633.10 mi (7,456.26 km) |
| Clay to Oestrich-Winkel | 4,666.70 mi (7,510.32 km) |
| Clay to Offenburg | 4,711.18 mi (7,581.92 km) |
| Clay to Oftersheim | 4,709.49 mi (7,579.19 km) |
| Clay to Ohrdruf | 4,748.06 mi (7,641.26 km) |
| Clay to Ohringen | 4,751.58 mi (7,646.92 km) |
| Clay to Olbernhau | 4,853.24 mi (7,810.53 km) |
| Clay to Olching | 4,857.23 mi (7,816.95 km) |
| Clay to Oldenburg | 4,580.91 mi (7,372.27 km) |
| Clay to Oldenburg in Holstein | 4,644.36 mi (7,474.37 km) |
| Clay to Olfen | 4,591.09 mi (7,388.65 km) |
| Clay to Olpe | 4,629.38 mi (7,450.27 km) |
| Clay to Olsberg | 4,644.68 mi (7,474.89 km) |
| Clay to Oranienburg | 4,779.51 mi (7,691.88 km) |
| Clay to Ortenberg | 4,697.54 mi (7,559.97 km) |
