| Barstow to Olympia Heights (Florida) | 2,265.21 mi (3,645.50 km) |
| Barstow to Omaha (Nebraska) | 1,220.73 mi (1,964.57 km) |
| Barstow to On Top of the World Designated Place (Florida) | 2,064.93 mi (3,323.18 km) |
| Barstow to Onalaska (Wisconsin) | 1,506.02 mi (2,423.70 km) |
| Barstow to Oneida (New York) | 2,269.73 mi (3,652.78 km) |
| Barstow to Oneonta (New York) | 2,300.22 mi (3,701.85 km) |
| Barstow to Ontario (California) | 65.41 mi (105.27 km) |
| Barstow to Ontario (Oregon) | 632.89 mi (1,018.54 km) |
| Barstow to Opa-locka (Florida) | 2,264.81 mi (3,644.85 km) |
| Barstow to Opelika (Alabama) | 1,817.96 mi (2,925.73 km) |
| Barstow to Opelousas (Louisiana) | 1,478.21 mi (2,378.94 km) |
| Barstow to Orange (California) | 85.68 mi (137.89 km) |
| Barstow to Orange (Texas) | 1,392.57 mi (2,241.13 km) |
| Barstow to Orange City (Florida) | 2,125.62 mi (3,420.85 km) |
| Barstow to Orangeburg (South Carolina) | 2,058.98 mi (3,313.60 km) |
