| Bargoed to Olympia Heights (Florida) | 4,302.61 mi (6,924.39 km) |
| Bargoed to Omaha (Nebraska) | 4,170.10 mi (6,711.13 km) |
| Bargoed to On Top of the World Designated Place (Florida) | 4,215.65 mi (6,784.43 km) |
| Bargoed to Onalaska (Wisconsin) | 3,866.23 mi (6,222.09 km) |
| Bargoed to Oneida (New York) | 3,297.63 mi (5,307.02 km) |
| Bargoed to Oneonta (New York) | 3,299.49 mi (5,310.01 km) |
| Bargoed to Ontario (California) | 5,310.67 mi (8,546.70 km) |
| Bargoed to Ontario (Oregon) | 4,735.40 mi (7,620.88 km) |
| Bargoed to Opa-locka (Florida) | 4,290.19 mi (6,904.40 km) |
| Bargoed to Opelika (Alabama) | 4,169.05 mi (6,709.44 km) |
| Bargoed to Opelousas (Louisiana) | 4,548.86 mi (7,320.68 km) |
| Bargoed to Orange (California) | 5,331.09 mi (8,579.56 km) |
| Bargoed to Orange (Texas) | 4,637.06 mi (7,462.63 km) |
| Bargoed to Orange City (Florida) | 4,182.13 mi (6,730.49 km) |
| Bargoed to Orangeburg (South Carolina) | 3,942.37 mi (6,344.63 km) |
