The ABS has an interesting document out that covers demographics [PDF] . It is a good read.

It has the populations of the major Australian cities;

• 4,254,894 : Sydney (NSW)
• 3,634,233 : Melbourne (Vic)
• 1,810,943 : Brisbane (Qld)
• 1,129,269 : Adelaide (SA)
• 1,477,815 : Perth (WA)
• 510,885 : Newcastle (NSW)
• 482,037 : Gold Coast-Tweed (Qld/NSW)
• 371,441 : Canberra-Queanbeyan (ACT/NSW)
• 275,883 : Wollongong (NSW)
• 212,864 : Sunshine Coast (Qld)
• 203,638 : Hobart (Tas)
• 165,761 : Geelong (Vic)
• 148,767 : Townsville (Qld)
• 123,408 : Cairns (Qld)

I can remember when I was young that the Greater Sydney Area had four million in it. I presume that was the Sydney basin and included Newcastle and Wollongong in it, though the 'gong being part of Sydney is a stretch.

Sydney is not growing by much, in the last five years it has grown less than one percent. Brisbane, Tweed, the Sunshine Coast, Townsville have all grown by over two percent with the the Gold Coast and Sunshine Coast being over three.

Sydney and Melbourne make up a big chunk of their states' populations as well. NSW has 6.8 million in it, while Victoria has just over five million.

In nearly all cases the capital city makes up more than half the state's population. I think this is a good graph that shows removing the states is unwise. The capital cities would remain well represented as their local councils would be large and powerful, but outside of the capital cities there would be a distinct lack of representation. The councils would have little voice to buffer themselves against the federal government.

From the ABS is the population statistics for the states. The 2007 stats haven't been released yet.

It is interesting to note on the report that population flows have been matching the states with booming economies. For instance, Western Australia, Queensland and the Northern Territory have to the largest changes over previous years with a 2.1% gain in WA. This suggests some mobility in the workforce in moving to opportunities though none of the states had negative changes, possibly due to immigration working to continue population increases.

Update: I take that last sentence back, oversea migration made up 52% of Western Australia's increase in population, there was almost no inter-state movement to WA either, it was all births or overseas migration. More at clubtroppo.