| Llantwit Major to Olympia Heights (Florida) | 4,295.06 mi (6,912.23 km) |
| Llantwit Major to Omaha (Nebraska) | 4,171.25 mi (6,712.99 km) |
| Llantwit Major to On Top of the World Designated Place (Florida) | 4,209.59 mi (6,774.67 km) |
| Llantwit Major to Onalaska (Wisconsin) | 3,867.15 mi (6,223.58 km) |
| Llantwit Major to Oneida (New York) | 3,294.78 mi (5,302.44 km) |
| Llantwit Major to Oneonta (New York) | 3,296.25 mi (5,304.80 km) |
| Llantwit Major to Ontario (California) | 5,315.21 mi (8,554.01 km) |
| Llantwit Major to Ontario (Oregon) | 4,742.10 mi (7,631.68 km) |
| Llantwit Major to Opa-locka (Florida) | 4,282.66 mi (6,892.28 km) |
| Llantwit Major to Opelika (Alabama) | 4,164.87 mi (6,702.71 km) |
| Llantwit Major to Opelousas (Louisiana) | 4,545.79 mi (7,315.75 km) |
| Llantwit Major to Orange (California) | 5,335.63 mi (8,586.87 km) |
| Llantwit Major to Orange (Texas) | 4,634.33 mi (7,458.23 km) |
| Llantwit Major to Orange City (Florida) | 4,175.75 mi (6,720.22 km) |
| Llantwit Major to Orangeburg (South Carolina) | 3,937.29 mi (6,336.45 km) |
