From Perth, the highway, signed as State Route 20,[1] starts from the Albany Highway junction in Armadale, 28 km from Perth, and follows a north–south route 20–30 km inland from the coast, passing through several agricultural and timber towns that sprang up in the 1890s when the nearby railway came through, such as Pinjarra, Waroona, Yarloop and Harvey.

The typical scenery on this part of the highway includes small dairy farms and orchards, jarrah and marri remnant forests and pine plantations.

This part of the highway, especially from Manjimup, is sparsely populated and very thickly forested, with abundant wildlife and wildflowers as well as many old growth trees, especially the giant karri.

The last stretch of approximately 12 miles (19 km) was the most dangerous for many years, as it required precarious crossings at the Collie and Preston Rivers.

[3]: 1–2 In an initial attempt to settle the area, the government declared the land open for pastoral settlement by ordinary settlers, but little progress was made.

[3]: 2  The settlement of Australind by the Western Australian Land Company in 1840–41 prompted the first real need for a good quality road to Perth.

[7][8] A bi-weekly mail route from Boyanup to Bridgetown via Preston, Balingup, and Greenbushes was established by 1891; it also extended further south to Balbarrup on a weekly basis.

[9] Surveying of a direct Bridgetown–Albany route was requested in January 1871, so that an electric telegraph line could be established, but the government surveyors were overwhelmed by other work.

By October 1921, £16,000 had been spent on upgrading the dirt track to a formed and gravelled road, with works expected to be completed over the 1921–22 summer at a cost of £2,000.

[14] The name was in common usage by March 1941,[15][16] and in July 1941, the name was officially applied to "the main road from Armadale to Pemberton via Pinjarra, Harvey, Picton Junction, Boyanup, Donnybrook, Bridgetown and Manjimup".