It seems that not a week goes by without reading an article that highlights the sea/tree change phenomenon. The tone of these articles suggests that people are leaving Sydney and Melbourne in such numbers that the streets are devoid of people and life - save the obligatory tumbleweed. Recent ABS data releases on internal migration have meant that more timely analysis of the ebbs and flows of people around the country is possible. So what exactly is happening? Let a demographer, not a property analyst, put it all into context.