| Llantrisant to Olympia Heights (Florida) | 4,298.15 mi (6,917.21 km) |
| Llantrisant to Omaha (Nebraska) | 4,170.25 mi (6,711.36 km) |
| Llantrisant to On Top of the World Designated Place (Florida) | 4,211.97 mi (6,778.51 km) |
| Llantrisant to Onalaska (Wisconsin) | 3,866.25 mi (6,222.13 km) |
| Llantrisant to Oneida (New York) | 3,295.64 mi (5,303.83 km) |
| Llantrisant to Oneonta (New York) | 3,297.29 mi (5,306.48 km) |
| Llantrisant to Ontario (California) | 5,312.64 mi (8,549.86 km) |
| Llantrisant to Ontario (Oregon) | 4,738.52 mi (7,625.92 km) |
| Llantrisant to Opa-locka (Florida) | 4,285.74 mi (6,897.24 km) |
| Llantrisant to Opelika (Alabama) | 4,166.37 mi (6,705.12 km) |
| Llantrisant to Opelousas (Louisiana) | 4,546.77 mi (7,317.31 km) |
| Llantrisant to Orange (California) | 5,333.06 mi (8,582.73 km) |
| Llantrisant to Orange (Texas) | 4,635.14 mi (7,459.54 km) |
| Llantrisant to Orange City (Florida) | 4,178.29 mi (6,724.30 km) |
| Llantrisant to Orangeburg (South Carolina) | 3,939.21 mi (6,339.54 km) |
