The A1 highway, also variously known as National Route 1, National Highway 1, and other names, circumnavigates Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

, mainly following the coastline, connecting all of the mainland state capitals. Refer to Highway 1

Highway 1 (Australia)

Australia's Highway 1 is a network of highways that circumnavigate the Australian continent, joining all mainland state capitals. At a total length of approximately it is the longest national highway in the world, longer than the Trans-Siberian Highway and the Trans-Canada Highway...

 for details.

Portions of the road have been upgraded to multi-lane dual-carriage-way motorway, and these sections are generally designated "M1

M1 (Australia)

The M1 is designated stretches of Australia's National Highway 1 that are: Dual-carriageway, Freeway or Motorway.Such stretches of highway include:-Queensland:* Bruce Highway from Cooroy to Bald Hills....

". Sections of the A1 between Sydney

Sydney

Sydney is the most populous city in Australia and the state capital of New South Wales. Sydney is located on Australia's south-east coast of the Tasman Sea. As of June 2010, the greater metropolitan area had an approximate population of 4.6 million people...

 and Port Augusta are also known as the Princes Highway

Princes Highway

The Princes Highway extends from Sydney to Port Augusta via the coast through the states of New South Wales, Victoria and South Australia, a distance of 1941 km or 1898 km via the former alignments of the highway ....

.

In South Australia

South Australia

South Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories.South Australia shares borders with all of the mainland...

, the A1/M1 connects:

• Mount Gambier
  • via Princes Highway
    Princes Highway
    The Princes Highway extends from Sydney to Port Augusta via the coast through the states of New South Wales, Victoria and South Australia, a distance of 1941 km or 1898 km via the former alignments of the highway ....
    
     to
• Murray Bridge
  • via South Eastern Freeway
    South Eastern Freeway
    The South Eastern Freeway is a 66 kilometre four-lane divided carriageway road in South Australia linking the Adelaide-Crafers Highway to the Princes Highway at the Swanport Bridge, a one kilometre long bridge over the River Murray, near Murray Bridge...
    
     to
• Crafers
  • via Adelaide–Crafers Highway to
• Glen Osmond
  • via Glen Osmond Road to
• Adelaide city centre
  Adelaide city centre
  The Adelaide city centre is the innermost locality of Greater Adelaide, known by locals simply as "The City" or "Town". The locality is split into two key geographical distinctions: the city "square mile", bordered by North, East, South and West Terraces; and that part of the Adelaide Parklands...
  
  
  • via Main North Road
    Main North Road
    Main North Road is the major north-south arterial route north of the city of Adelaide, South Australia.From the Adelaide city centre, it passes through the Adelaide Parklands and the suburbs of Thorngate, Medindie, Medindie Gardens, Nailsworth, Prospect, Sefton Park, Blair Athol and Enfield before...
    
     to
• Gepps Cross
  • via Port Wakefield Road
    Port Wakefield Road
    Port Wakefield Road is an important Australian highway. It connects Adelaide, the South Australian capital, to the Yorke Peninsula, Port Augusta, northern and western South Australia, the Northern Territory and Western Australia. It is designated National Highway A1 and a part of the National Highway...
    
     to
• Port Wakefield
  • via Princes Highway
    Princes Highway
    The Princes Highway extends from Sydney to Port Augusta via the coast through the states of New South Wales, Victoria and South Australia, a distance of 1941 km or 1898 km via the former alignments of the highway ....
    
     to
• Port Augusta
  • via Eyre Highway
    Eyre Highway
    The Eyre Highway is a highway linking Western Australia and South Australia via the Nullarbor Plain. Signed as National Highway 1/A1, it forms part of Highway 1 and the Australian National Highway network linking Perth and Adelaide. It was named after explorer Edward John Eyre, who was the first to...
    
     to
• Eucla