| Highgate to Olympia Heights (Florida) | 4,435.12 mi (7,137.64 km) |
| Highgate to Omaha (Nebraska) | 4,287.86 mi (6,900.65 km) |
| Highgate to On Top of the World Designated Place (Florida) | 4,347.04 mi (6,995.88 km) |
| Highgate to Onalaska (Wisconsin) | 3,984.69 mi (6,412.74 km) |
| Highgate to Oneida (New York) | 3,424.67 mi (5,511.47 km) |
| Highgate to Oneonta (New York) | 3,427.20 mi (5,515.55 km) |
| Highgate to Ontario (California) | 5,417.24 mi (8,718.21 km) |
| Highgate to Ontario (Oregon) | 4,833.56 mi (7,778.86 km) |
| Highgate to Opa-locka (Florida) | 4,422.69 mi (7,117.63 km) |
| Highgate to Opelika (Alabama) | 4,298.16 mi (6,917.22 km) |
| Highgate to Opelousas (Louisiana) | 4,676.14 mi (7,525.53 km) |
| Highgate to Orange (California) | 5,437.64 mi (8,751.04 km) |
| Highgate to Orange (Texas) | 4,763.75 mi (7,666.51 km) |
| Highgate to Orange City (Florida) | 4,313.81 mi (6,942.41 km) |
| Highgate to Orangeburg (South Carolina) | 4,072.69 mi (6,554.37 km) |
