Why two-thirds of Australians live in just one corner

Countries & Cities · Published 1 November 2026 Swipe more like this →

In short: Australia is famously flat, yet its population distribution is strikingly lopsided. Most of the nation's people cluster in the southeast—a geographic fluke driven by mountain rain shadows and ancient ice age flooding that turned a specific coastal strip into the continent's most habitable cradle.

The concentration of Australia's population in the southeast is dictated by the Great Dividing Range. This massive mountain system acts as a 'water tower,' forcing moist air from the Tasman Sea and Southern Ocean upward to create orographic rainfall. While northern regions are pushed into arid zones by global Hadley Cell circulation—where dry air descends around 30 degrees latitude—southern Victoria sits far enough south to escape this desert belt, receiving significantly higher rainfall than the interior. The landscape's evolution is also a story of rising seas. During the last Ice Age, sea levels were so low that Tasmania was connected to the mainland and Bass Strait was exposed land. As the climate warmed, the ocean flooded these low-lying valleys, creating 'drowned' landscapes like Port Phillip Bay.

This specific combination of sheltered bays, river systems like the Yarra, and fertile plains provided the geographic foundation for Melbourne’s development. Further east, regions like Gippsland showcase complex coastal processes where freshwater rivers meet tidal waters behind sandy barriers like Ninety Mile Beach. These interactions between sediment movement, sea-level change, and mountain runoff create some of Australia's most diverse ecosystems. Across a linked network, Victoria's southeast region operates as an integrated unit; alpine heights produce water, waterways carve terrain, and encroaching oceans mark where people establish settlements.

The Murray-Darling drainage basin highlights the contrast between these regions; while it is one of the world's largest river systems, covering nearly a third of Australia, it primarily drains arid land prone to drought. In contrast, the lush green farmlands and forested hillsides of the Great Divide benefit from consistent moisture, explaining why the nation's economic heartland remains anchored in these well-watered southern fringes.

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