Australia's national 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 (11,000 km or 6,800 mi) and the Trans-Canada Highway (8,030 km or 4,990 mi).

It was created as part of the National Route Numbering system, adopted in 1955. Many of the other national routes are tributaries of Highway 1.

US 20 is a coast-to-coast route and major route spanning 3,365 miles (5,415 km), it is the longest road in the United States.

More Info: en.wikipedia.org