| Idrija to Olympia Heights (Florida) | 5,158.33 mi (8,301.52 km) |
| Idrija to Omaha (Nebraska) | 5,032.26 mi (8,098.64 km) |
| Idrija to On Top of the World Designated Place (Florida) | 5,081.84 mi (8,178.43 km) |
| Idrija to Onalaska (Wisconsin) | 4,730.10 mi (7,612.37 km) |
| Idrija to Oneida (New York) | 4,172.69 mi (6,715.29 km) |
| Idrija to Oneonta (New York) | 4,174.40 mi (6,718.05 km) |
| Idrija to Ontario (California) | 6,138.18 mi (9,878.45 km) |
| Idrija to Ontario (Oregon) | 5,533.06 mi (8,904.60 km) |
| Idrija to Opa-locka (Florida) | 5,146.14 mi (8,281.92 km) |
| Idrija to Opelika (Alabama) | 5,042.59 mi (8,115.26 km) |
| Idrija to Opelousas (Louisiana) | 5,423.87 mi (8,728.88 km) |
| Idrija to Orange (California) | 6,158.50 mi (9,911.14 km) |
| Idrija to Orange (Texas) | 5,512.11 mi (8,870.88 km) |
| Idrija to Orange City (Florida) | 5,046.50 mi (8,121.55 km) |
| Idrija to Orangeburg (South Carolina) | 4,813.23 mi (7,746.15 km) |
