Most of these rural roads, especially in the Wheatbelt, connected farms to the state government's extensive rail network, usually covering a distance of less than 20 miles (32 km).

The board worked in cooperation with local governments, taking over the development of significant roads, and providing assistance for others.

District offices were set up in regional areas to better coordinate work undertaken there, and liaise with those local governments.

With the outbreak of World War II in 1939, a smaller labour force undertook works for Main Roads, which were primarily for military purposes, such as aerodromes and parade grounds.

Government funding and support increased, and new equipment such as power graders, front-end loaders, and large trucks allowed work to be undertaken more efficiently.

The amount of work meant there was a high demand for workers – the re-established regional divisions became employment hubs for European migrants.