 Eyre Highway begins at the town of Norseman , on the Coolgardie – Esperance Highway . Apart from Eucla , 12 kilometres ( 7 @.@ 5 mi ) from the South Australia border , roadhouses serving the highway are the only settlements on the 720 @-@ kilometre @-@ long ( 450 mi ) stretch through Western Australia . These are located 65 to 180 kilometres ( 40 to 110 mi ) apart , at Balladonia , Caiguna , Cocklebiddy , Madura , and <unk> . The section between Balladonia and Caiguna includes what is regarded as the longest straight stretch of road in Australia and one of the longest in the world . The road stretches for 145 @.@ 6 kilometres ( 90 @.@ 5 mi ) without turning , and is signposted and commonly known as the " 90 Mile Straight " . Travelling east , the highway descends through the Madura Pass just before the Madura roadhouse from the Nullarbor Plain to the coastal Roe Plains . It skirts the bottom of the escarpment , climbing back through the Eucla Pass just before Eucla . 
