The name is not formally designated but is widely used to refer to an area of approximately 20,000 square kilometres (7700 square miles) bounded by the River Murray[note 1] on its northern and western sides, the Victorian border on its eastern side, and up to about 50 kilometres (30 miles) south of the Mallee Highway.
The Murray Mallee area is predominantly a vast plain of low elevation, with sandhills and gentle undulating sandy rises, interspersed by flats.
The area was very lightly populated, with marginal pastoral runs of sheep at low stocking rates, until the beginning of the 20th century.
[citation needed] Artesian water was discovered at moderate depth, and 707 kilometres (439 miles) of railways were opened, mainly in the 1910s, to make shipping of grain economically feasible.
Large expanses – estimates are about 80% – of the mallee country were cleared for agricultural development, beginning as early as the 1880s.