| Castagneto Carducci to Olympia Heights (Florida) | 5,069.46 mi (8,158.51 km) |
| Castagneto Carducci to Omaha (Nebraska) | 5,036.77 mi (8,105.90 km) |
| Castagneto Carducci to On Top of the World Designated Place (Florida) | 5,009.36 mi (8,061.79 km) |
| Castagneto Carducci to Onalaska (Wisconsin) | 4,732.00 mi (7,615.41 km) |
| Castagneto Carducci to Oneida (New York) | 4,136.57 mi (6,657.17 km) |
| Castagneto Carducci to Oneonta (New York) | 4,134.38 mi (6,653.64 km) |
| Castagneto Carducci to Ontario (California) | 6,182.25 mi (9,949.37 km) |
| Castagneto Carducci to Ontario (Oregon) | 5,599.71 mi (9,011.86 km) |
| Castagneto Carducci to Opa-locka (Florida) | 5,057.63 mi (8,139.47 km) |
| Castagneto Carducci to Opelika (Alabama) | 4,990.33 mi (8,031.17 km) |
| Castagneto Carducci to Opelousas (Louisiana) | 5,382.65 mi (8,662.53 km) |
| Castagneto Carducci to Orange (California) | 6,202.66 mi (9,982.21 km) |
| Castagneto Carducci to Orange (Texas) | 5,474.30 mi (8,810.04 km) |
| Castagneto Carducci to Orange City (Florida) | 4,970.80 mi (7,999.73 km) |
| Castagneto Carducci to Orangeburg (South Carolina) | 4,752.25 mi (7,648.00 km) |
