| Zachary to Olympia (Washington) | 2,026.62 mi (3,261.52 km) |
| Zachary to Olympia Heights (Florida) | 741.77 mi (1,193.77 km) |
| Zachary to Omaha (Nebraska) | 781.30 mi (1,257.38 km) |
| Zachary to On Top of the World Designated Place (Florida) | 542.40 mi (872.91 km) |
| Zachary to Onalaska (Wisconsin) | 913.69 mi (1,470.45 km) |
| Zachary to Oneida (New York) | 1,208.43 mi (1,944.78 km) |
| Zachary to Oneonta (New York) | 1,205.15 mi (1,939.50 km) |
| Zachary to Ontario (California) | 1,556.53 mi (2,505.00 km) |
| Zachary to Ontario (Oregon) | 1,680.72 mi (2,704.87 km) |
| Zachary to Opa-locka (Florida) | 740.35 mi (1,191.48 km) |
| Zachary to Opelika (Alabama) | 367.13 mi (590.84 km) |
| Zachary to Opelousas (Louisiana) | 55.45 mi (89.24 km) |
| Zachary to Orange (California) | 1,568.62 mi (2,524.45 km) |
| Zachary to Orange (Texas) | 159.25 mi (256.29 km) |
| Zachary to Orange City (Florida) | 603.81 mi (971.74 km) |
