| Clayton to Orbetello | 984.30 mi (1,584.08 km) |
| Clayton to Oria | 1,286.98 mi (2,071.20 km) |
| Clayton to Oristano | 1,074.91 mi (1,729.89 km) |
| Clayton to Orta Nova | 1,180.23 mi (1,899.39 km) |
| Clayton to Orte | 1,016.38 mi (1,635.71 km) |
| Clayton to Ortona | 1,083.28 mi (1,743.37 km) |
| Clayton to Orvieto | 993.74 mi (1,599.26 km) |
| Clayton to Orzinuovi | 780.46 mi (1,256.02 km) |
| Clayton to Osimo | 993.07 mi (1,598.19 km) |
| Clayton to Ospitaletto | 776.23 mi (1,249.23 km) |
| Clayton to Ostuni | 1,272.69 mi (2,048.20 km) |
| Clayton to Ottaviano | 1,169.34 mi (1,881.87 km) |
| Clayton to Ovada | 786.91 mi (1,266.41 km) |
| Clayton to Ozieri | 1,041.10 mi (1,675.49 km) |
| Clayton to Paceco | 1,286.40 mi (2,070.26 km) |
