| Slovenj Gradec to Olympia Heights (Florida) | 5,192.14 mi (8,355.94 km) |
| Slovenj Gradec to Omaha (Nebraska) | 5,045.53 mi (8,120.00 km) |
| Slovenj Gradec to On Top of the World Designated Place (Florida) | 5,112.23 mi (8,227.33 km) |
| Slovenj Gradec to Onalaska (Wisconsin) | 4,744.18 mi (7,635.03 km) |
| Slovenj Gradec to Oneida (New York) | 4,195.75 mi (6,752.41 km) |
| Slovenj Gradec to Oneonta (New York) | 4,198.33 mi (6,756.56 km) |
| Slovenj Gradec to Ontario (California) | 6,141.42 mi (9,883.65 km) |
| Slovenj Gradec to Ontario (Oregon) | 5,531.19 mi (8,901.58 km) |
| Slovenj Gradec to Opa-locka (Florida) | 5,179.89 mi (8,336.22 km) |
| Slovenj Gradec to Opelika (Alabama) | 5,068.63 mi (8,157.17 km) |
| Slovenj Gradec to Opelousas (Louisiana) | 5,447.26 mi (8,766.51 km) |
| Slovenj Gradec to Orange (California) | 6,161.70 mi (9,916.29 km) |
| Slovenj Gradec to Orange (Texas) | 5,534.68 mi (8,907.21 km) |
| Slovenj Gradec to Orange City (Florida) | 5,077.59 mi (8,171.59 km) |
| Slovenj Gradec to Orangeburg (South Carolina) | 4,841.30 mi (7,791.32 km) |
