| Montemor-o-Novo to Olympia Heights (Florida) | 4,204.44 mi (6,766.39 km) |
| Montemor-o-Novo to Omaha (Nebraska) | 4,440.89 mi (7,146.92 km) |
| Montemor-o-Novo to On Top of the World Designated Place (Florida) | 4,186.23 mi (6,737.09 km) |
| Montemor-o-Novo to Onalaska (Wisconsin) | 4,137.99 mi (6,659.45 km) |
| Montemor-o-Novo to Oneida (New York) | 3,441.32 mi (5,538.26 km) |
| Montemor-o-Novo to Oneonta (New York) | 3,427.04 mi (5,515.28 km) |
| Montemor-o-Novo to Ontario (California) | 5,683.31 mi (9,146.40 km) |
| Montemor-o-Novo to Ontario (Oregon) | 5,203.90 mi (8,374.86 km) |
| Montemor-o-Novo to Opa-locka (Florida) | 4,193.64 mi (6,749.01 km) |
| Montemor-o-Novo to Opelika (Alabama) | 4,222.12 mi (6,794.85 km) |
| Montemor-o-Novo to Opelousas (Louisiana) | 4,636.16 mi (7,461.19 km) |
| Montemor-o-Novo to Orange (California) | 5,703.38 mi (9,178.70 km) |
| Montemor-o-Novo to Orange (Texas) | 4,735.36 mi (7,620.83 km) |
| Montemor-o-Novo to Orange City (Florida) | 4,140.16 mi (6,662.94 km) |
| Montemor-o-Novo to Orangeburg (South Carolina) | 3,965.48 mi (6,381.83 km) |
