Nine-tenths of the unoccupied area is located in Western Australia, Northern Territory, and South Australia. This large area includes chiefly the sand-ridge deserts and bordering lands. Most of the unoccupied area lies within the 10-in-rainfall line except in the north, where areas with greater amounts of summer precipitation are included. Most of the Nullarbor Plain to the south is also included because its occupancy is difficult owing to the scarcity of surface water. Some extremely rugged land is unoccupied in Arnhem Land and in the Kimberlies.
The occupied area includes two major types of land, (1) the pastoral country and (2) the land suitable for crop production, forests, improved pasture, and close settlement. Many sheep are grown in both divisions, but beef cattle are restricted chiefly to the pastoral districts. Farmers are tempted in times of high prices and sufficient rainfall to expand into the pastoral country. Pastoralists are tempted under similar circumstances to push their way into the normally unoccupied areas. Those boundaries are zones of advance and retreat, and brief success is commonly followed by quick defeat. It now appears that both farmers and pastoralists have pushed their boundaries too far into the dry lands, and a gradual retreat might be the desirable direction for the immediate future. There is little prospect that many more people can be supported by animal and crop production in these interior districts. The hope for future settlement lies instead in the intensification of output in the best pastoral and agricultural districts.