Joining all mainland state capitals of Australia, Highway 1 is the Longest national Highway in the world. It is located in Australia and has a total length of approximately 14,500 km. Highway 1, not to be confused with the National Highway, is Australia’s coastal highway, covering New South Wales, Victoria, South Australia, Western Australia, the Northern Territory and Tasmania. Stick to Highway 1’s network of freeways, expressways and unsealed tracks and you can circumnavigate the entire country.

Highway 1 was the only true national highway but with the introduction of the National Highway system in 1974, the significance of Highway 1 diminished. Large sections of Highway 1 are shared with the Australian National Highway, though the two are not synonymous. With such a vast and incomparable length, road conditions vary greatly; from multi-lane freeways in populous urban and rural areas, to sealed two-laners in remote areas.

In 1955 National Route Numbering System was adopted and Highway 1 was created as a part of it. An existing network of state and local roads and tracks compiles the route of Highway 1. Except the Australian Capital Territory, Highway 1 reach all Australian States and territories and is only route to do so. Certain major traffic routes that ran parallel to the main route under the original Highway 1 scheme. These routes were designated National Route Alternative 1. A state route designation or an alpha-numeric route designation replace most of these route designations and the old Princes Highway route from Dandenong to South Melbourne in Victoria is an example of that.

Highway 1 starts from sydney from where it heads to Adelaide via the Eastern Distributor, Southern Cross Drive, General Holmes Drive, The Grand Parade, President Avenue, Princes Highway (NSW), Princes Motorway, Princes Highway (VIC), Princes Freeway (east), Monash Freeway, CityLink, West Gate Freeway, Princes Freeway (west), Geelong Ring Road, Princes Highway (SA) and from there it head on to Perth via Port Wakefield Road, Augusta Highway, Eyre Highway, Coolgardie-Esperance Highway, South Coast Highway and South Western Highway. From there Highway 1 heads to to Darwin via Brand Highway, North West Coastal Highway, Great Northern Highway, Victoria Highway, and Stuart Highway. From darwin, Highway 1 follows the Stuart Highway to Daly Waters, and thereafter the Carpentaria Highway to Borroloola. From there it tracks from the Gulf Developmental Road and Kennedy Highway to Cairns via Bruce Highway to Brisbane and then back to Sydney via the Pacific Motorway (QLD/NSW), Pacific Highway (NSW), Pacific Motorway (NSW), Pacific Highway (Sydney), Gore Hill Freeway, Warringah Freeway, Sydney Harbour Tunnel, and the Cahill Expressway. From Brooker highway in hobart it heads toward Launceston via the Midland Highway. Then it becomes the Bass Highway to Burnie. Highway 1 ends at Burnie.

The highways in the 2nd and 3rd position are

2nd : Trans-Siberian Highway in Russia. Total Length - Over 11,000 kilometres.
3rd : Trans-Canada Highway in Canada. Total Length - Over 8,030 kilometres.