| Castel San Giorgio to Odessa (Texas) | 6,009.94 mi (9,672.06 km) |
| Castel San Giorgio to Ogden (Utah) | 5,859.97 mi (9,430.71 km) |
| Castel San Giorgio to Oildale (California) | 6,407.85 mi (10,312.44 km) |
| Castel San Giorgio to Ojus (Florida) | 5,306.94 mi (8,540.69 km) |
| Castel San Giorgio to Okemos (Michigan) | 4,782.17 mi (7,696.16 km) |
| Castel San Giorgio to Oklahoma City (Oklahoma) | 5,638.87 mi (9,074.88 km) |
| Castel San Giorgio to Okmulgee (Oklahoma) | 5,571.38 mi (8,966.28 km) |
| Castel San Giorgio to Olathe (Kansas) | 5,368.30 mi (8,639.44 km) |
| Castel San Giorgio to Old Jamestown (Missouri) | 5,188.82 mi (8,350.60 km) |
| Castel San Giorgio to Oldsmar (Florida) | 5,334.40 mi (8,584.89 km) |
| Castel San Giorgio to Olean (New York) | 4,558.74 mi (7,336.58 km) |
| Castel San Giorgio to Olive Branch (Mississippi) | 5,346.65 mi (8,604.60 km) |
| Castel San Giorgio to Olivehurst (California) | 6,269.32 mi (10,089.50 km) |
| Castel San Giorgio to Olney (Maryland) | 4,614.25 mi (7,425.92 km) |
| Castel San Giorgio to Olympia (Washington) | 5,833.68 mi (9,388.40 km) |
