| Portogruaro to Olympia Heights (Florida) | 5,110.13 mi (8,223.95 km) |
| Portogruaro to Omaha (Nebraska) | 4,999.76 mi (8,046.33 km) |
| Portogruaro to On Top of the World Designated Place (Florida) | 5,036.04 mi (8,104.72 km) |
| Portogruaro to Onalaska (Wisconsin) | 4,696.98 mi (7,559.06 km) |
| Portogruaro to Oneida (New York) | 4,132.46 mi (6,650.56 km) |
| Portogruaro to Oneonta (New York) | 4,133.51 mi (6,652.25 km) |
| Portogruaro to Ontario (California) | 6,114.10 mi (9,839.69 km) |
| Portogruaro to Ontario (Oregon) | 5,513.72 mi (8,873.47 km) |
| Portogruaro to Opa-locka (Florida) | 5,097.99 mi (8,204.42 km) |
| Portogruaro to Opelika (Alabama) | 4,999.97 mi (8,046.67 km) |
| Portogruaro to Opelousas (Louisiana) | 5,383.21 mi (8,663.43 km) |
| Portogruaro to Orange (California) | 6,134.44 mi (9,872.43 km) |
| Portogruaro to Orange (Texas) | 5,472.05 mi (8,806.42 km) |
| Portogruaro to Orange City (Florida) | 5,000.20 mi (8,047.04 km) |
| Portogruaro to Orangeburg (South Carolina) | 4,769.14 mi (7,675.18 km) |
