As of 2018, which country has the longest drivable national highway in the world?

Australia's Highway 1 is a network of highways that circumnavigate the country, joining all mainland state capitals. At a total length of approximately 14,500 km (9,000 mi) it is the longest national highway in the world, surpassing the Trans-Siberian Highway (over 11,000 km or 6,800 mi) and the Trans-Canada Highway (8,030 km or 4,990 mi). Every day more than a million people travel on a part of it.

Highway 1 was created as part of the National Route Numbering system, adopted in 1955. The route was compiled from an existing network of state and local roads and tracks. Highway 1 is the only route to reach across all Australian states and territories, with the exception of the Australian Capital Territory. Many of the other national routes are tributaries of Highway 1.

Under the original Highway 1 scheme, certain major traffic routes that ran parallel to the main route were designated National Route Alternative 1.

On the 18th June 2017 team 'Highway 1 to Hell' set a new record for a complete lap of Australia. While there have been previous attempts (notably 'Motor Magazine's' 2004 record of 6 days, 8 hours and 52 minutes) which skipped inland direct to Mt Isa, the 'Highway 1 to Hell' team travelled the route of Highway 1 (skipping Tasmania's stretch of road and therefore totalling 14280km) in 5 days, 13 hours and 43 minutes.