| Placentia to Olympia (Washington) | 946.63 mi (1,523.45 km) |
| Placentia to Olympia Heights (Florida) | 2,305.21 mi (3,709.87 km) |
| Placentia to Omaha (Nebraska) | 1,293.74 mi (2,082.07 km) |
| Placentia to On Top of the World Designated Place (Florida) | 2,110.77 mi (3,396.96 km) |
| Placentia to Onalaska (Wisconsin) | 1,581.77 mi (2,545.61 km) |
| Placentia to Oneida (New York) | 2,342.23 mi (3,769.45 km) |
| Placentia to Oneonta (New York) | 2,371.94 mi (3,817.27 km) |
| Placentia to Ontario (California) | 17.99 mi (28.95 km) |
| Placentia to Ontario (Oregon) | 702.54 mi (1,130.63 km) |
| Placentia to Opa-locka (Florida) | 2,305.24 mi (3,709.93 km) |
| Placentia to Opelika (Alabama) | 1,870.30 mi (3,009.96 km) |
| Placentia to Opelousas (Louisiana) | 1,520.49 mi (2,446.99 km) |
| Placentia to Orange (California) | 5.65 mi (9.09 km) |
| Placentia to Orange (Texas) | 1,432.01 mi (2,304.60 km) |
| Placentia to Orange City (Florida) | 2,171.75 mi (3,495.10 km) |
