Gee....I didn't know there were more big cities in Austrailia than Sydney, Melbourne, New Castle, Canberra, Perth, Hobart, Townsville, Brisbane and Darwin(which is about the size of Cheyenne or Greley). Although all those towns together are about 10 mil and there are 20 million Austrailians...and 20 million people in a country that seems to be at least 2 million sq miles seems to be a bit lonely. Only twice the population density of Wyoming..
Basically, half the aussie population lives in Melbourne or Sydney or their surrounds. IIRC the order is:
Sydney, Melbourne, Brisbane, Perth, Adelaide, Gold Coast, Canberra, Newcastle, Gosford, Wollongong. Geelong, Hobart and Cairns all have over 100,000 as well, and maybe a few more here and there.