South West Highway is in Western Australia. It starts in Metropolitan Perth, and travels along a route that is parallel with the railway to Bunbury, then from outside Bunbury it travels through Donnybrook, Bridgetown, Manjimup, and through forests to Walpole, where it connects with the South Coastal highway. It has been a route from Perth to Albany that is considered a cooler and more interesting travelling through forests compared to the other major routes - Albany Highway and Great Southern Highway.
South Western Highway was the first main road out of Perth into the south west, it was followed by the roads to the west later on. As it was developed in the time of the importance of railways, it gave access to the railway towns of Pinjarra and Brunswick Junction (where the trains to the Collie coal-fields joined into the railway system). As a consequence it is a twisting and turning highway that has been slowly developed in comparison to the very big money roads of the coast road and Bunbury highways.
After it turns inland from outside of Bunbury, it climbs the hills in more or less the same route that the old railway that went to Manjimup. After Manjimup it travels deep into the forest area of the southern coast, till it reaches Walpole, where it changes into the South Coastal Highway.
The forests that the highway passes through are the largest, with the tallest trees in the state of Western Australia.
- At Walpole the South Coast Highway continues towards Denmark and Albany