| Hertford to Olympia Heights (Florida) | 4,435.40 mi (7,138.08 km) |
| Hertford to Omaha (Nebraska) | 4,282.03 mi (6,891.27 km) |
| Hertford to On Top of the World Designated Place (Florida) | 4,346.21 mi (6,994.55 km) |
| Hertford to Onalaska (Wisconsin) | 3,979.04 mi (6,403.65 km) |
| Hertford to Oneida (New York) | 3,421.62 mi (5,506.57 km) |
| Hertford to Oneonta (New York) | 3,424.42 mi (5,511.08 km) |
| Hertford to Ontario (California) | 5,409.14 mi (8,705.16 km) |
| Hertford to Ontario (Oregon) | 4,824.18 mi (7,763.76 km) |
| Hertford to Opa-locka (Florida) | 4,422.94 mi (7,118.03 km) |
| Hertford to Opelika (Alabama) | 4,295.97 mi (6,913.70 km) |
| Hertford to Opelousas (Louisiana) | 4,673.15 mi (7,520.71 km) |
| Hertford to Orange (California) | 5,429.53 mi (8,737.99 km) |
| Hertford to Orange (Texas) | 4,760.51 mi (7,661.31 km) |
| Hertford to Orange City (Florida) | 4,313.21 mi (6,941.45 km) |
| Hertford to Orangeburg (South Carolina) | 4,071.17 mi (6,551.91 km) |
