Highway 1 continues around the rest of Australia, joining all mainland state capitals, and connecting major centres in Tasmania.

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.

In 1958, it was extended northward from Adelaide to Port Augusta, and westward, toward the Eyre/Lincoln highway junction.

The Eyre Highway, the Port Wakefield-Port Augusta Road, Port Wakefield Road, and the South Eastern Freeway were declared National Highways in November 1974.