| Idanha-a-Nova to Olympia Heights (Florida) | 4,239.53 mi (6,822.87 km) |
| Idanha-a-Nova to Omaha (Nebraska) | 4,436.51 mi (7,139.87 km) |
| Idanha-a-Nova to On Top of the World Designated Place (Florida) | 4,213.99 mi (6,781.76 km) |
| Idanha-a-Nova to Onalaska (Wisconsin) | 4,132.47 mi (6,650.57 km) |
| Idanha-a-Nova to Oneida (New York) | 3,447.25 mi (5,547.81 km) |
| Idanha-a-Nova to Oneonta (New York) | 3,434.68 mi (5,527.59 km) |
| Idanha-a-Nova to Ontario (California) | 5,670.64 mi (9,126.01 km) |
| Idanha-a-Nova to Ontario (Oregon) | 5,178.53 mi (8,334.04 km) |
| Idanha-a-Nova to Opa-locka (Florida) | 4,228.53 mi (6,805.16 km) |
| Idanha-a-Nova to Opelika (Alabama) | 4,241.13 mi (6,825.44 km) |
| Idanha-a-Nova to Opelousas (Louisiana) | 4,652.83 mi (7,488.01 km) |
| Idanha-a-Nova to Orange (California) | 5,690.80 mi (9,158.45 km) |
| Idanha-a-Nova to Orange (Texas) | 4,751.14 mi (7,646.22 km) |
| Idanha-a-Nova to Orange City (Florida) | 4,169.09 mi (6,709.51 km) |
| Idanha-a-Nova to Orangeburg (South Carolina) | 3,986.80 mi (6,416.14 km) |
