In Western Australia, Highway 1 is a 5,305-kilometre (3,296 mi) long route around the state, from the South Australian border near Eucla to the Northern Territory border near Kununurra. Highway 1 continues around the rest of Australia, joining all mainland state capitals, and connecting major centres in Tasmania. All roads within the Highway 1 system are allocated a road route numbered 1, M1, A1, or B1, depending on the state route numbering system. In Western Australia, most of the highway is designated as National Route 1; however, the sections in the north-east and south-east of the state that are concurrent with the National Highway routes linking Perth to Adelaide and Darwin are designated as National Highway 1.

Eyre Highway is a 1,664-kilometre (1,034 mi) highway linking Western Australia and South Australia via the Nullarbor Plain. Signed as National Highways 1 and 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 European to cross the Nullarbor by land, in 1840–1841. Eyre Highway runs from Norseman in Western Australia, past Eucla, to the state border. Continuing to the South Australian town of Ceduna, it crosses the top of the Eyre Peninsula before reaching Port Augusta.