| Calexico to Olympia Heights (Florida) | 2,163.68 mi (3,482.11 km) |
| Calexico to Omaha (Nebraska) | 1,221.92 mi (1,966.49 km) |
| Calexico to On Top of the World Designated Place (Florida) | 1,976.29 mi (3,180.54 km) |
| Calexico to Onalaska (Wisconsin) | 1,519.24 mi (2,444.99 km) |
| Calexico to Oneida (New York) | 2,263.66 mi (3,643.01 km) |
| Calexico to Oneonta (New York) | 2,290.59 mi (3,686.35 km) |
| Calexico to Ontario (California) | 153.65 mi (247.28 km) |
| Calexico to Ontario (Oregon) | 787.65 mi (1,267.60 km) |
| Calexico to Opa-locka (Florida) | 2,164.18 mi (3,482.92 km) |
| Calexico to Opelika (Alabama) | 1,745.66 mi (2,809.36 km) |
| Calexico to Opelousas (Louisiana) | 1,382.97 mi (2,225.68 km) |
| Calexico to Orange (California) | 155.12 mi (249.64 km) |
| Calexico to Orange (Texas) | 1,291.54 mi (2,078.54 km) |
| Calexico to Orange City (Florida) | 2,037.55 mi (3,279.13 km) |
| Calexico to Orangeburg (South Carolina) | 1,995.93 mi (3,212.14 km) |
