| Holyhead to Orangevale (California) | 5,043.31 mi (8,116.42 km) |
| Holyhead to Orchards (Washington) | 4,681.74 mi (7,534.52 km) |
| Holyhead to Orcutt (California) | 5,237.90 mi (8,429.58 km) |
| Holyhead to Oregon (Ohio) | 3,572.76 mi (5,749.81 km) |
| Holyhead to Oregon (Wisconsin) | 3,739.30 mi (6,017.83 km) |
| Holyhead to Oregon City (Oregon) | 4,703.16 mi (7,569.00 km) |
| Holyhead to Orem (Utah) | 4,654.38 mi (7,490.50 km) |
| Holyhead to Orinda (California) | 5,118.54 mi (8,237.50 km) |
| Holyhead to Orland Park (Illinois) | 3,743.99 mi (6,025.37 km) |
| Holyhead to Orlando (Florida) | 4,131.29 mi (6,648.66 km) |
| Holyhead to Ormond Beach (Florida) | 4,079.81 mi (6,565.81 km) |
| Holyhead to Oro Valley (Arizona) | 5,061.98 mi (8,146.47 km) |
| Holyhead to Oroville (California) | 5,007.05 mi (8,058.07 km) |
| Holyhead to Oshkosh (Wisconsin) | 3,657.59 mi (5,886.32 km) |
| Holyhead to Oskaloosa (Iowa) | 3,937.73 mi (6,337.17 km) |
