| Rancho San Diego to Olympia (Washington) | 1,035.41 mi (1,666.33 km) |
| Rancho San Diego to Olympia Heights (Florida) | 2,246.70 mi (3,615.72 km) |
| Rancho San Diego to Omaha (Nebraska) | 1,287.78 mi (2,072.48 km) |
| Rancho San Diego to On Top of the World Designated Place (Florida) | 2,058.90 mi (3,313.48 km) |
| Rancho San Diego to Onalaska (Wisconsin) | 1,582.11 mi (2,546.16 km) |
| Rancho San Diego to Oneida (New York) | 2,332.70 mi (3,754.13 km) |
| Rancho San Diego to Oneonta (New York) | 2,360.56 mi (3,798.96 km) |
| Rancho San Diego to Ontario (California) | 96.71 mi (155.64 km) |
| Rancho San Diego to Ontario (Oregon) | 778.24 mi (1,252.45 km) |
| Rancho San Diego to Opa-locka (Florida) | 2,247.19 mi (3,616.51 km) |
| Rancho San Diego to Opelika (Alabama) | 1,826.85 mi (2,940.04 km) |
| Rancho San Diego to Opelousas (Louisiana) | 1,465.78 mi (2,358.95 km) |
| Rancho San Diego to Orange (California) | 88.84 mi (142.97 km) |
| Rancho San Diego to Orange (Texas) | 1,374.52 mi (2,212.07 km) |
| Rancho San Diego to Orange City (Florida) | 2,120.14 mi (3,412.03 km) |
