Sydney has long been Australia’s most populous city, but last week, Melbourne officially overtook it – thanks to a quirk in how the figures are counted.
Melbourne’s population was 4,875,400 at the country’s most recent census in 2021, while there were 18,700 fewer people in Sydney, according to data from the Australian Bureau of Statistics (ABS) which returns Melbourne to the mantle of Australia’s most populous city, a title it last held in 1905.
Melbourne’s growth had been outpacing Sydney’s for much of the last decade, in part due to international and internal migration patterns that favoured the southern city.
Melbourne’s leap to the top spot was sudden. Initial census results had Sydney ahead, but on Thursday, the ABS updated a boundary it used to calculate Melbourne’s population, and the city expanded to take in a formerly regional patch – Melton – on its north-west fringe.
This was due to one of the main methods the ABS uses to tally population. The “significant urban area” measure defines a city’s boundary by contiguous urban population above 10,000.
As the ABS continued to process the census data, it calculated the population threshold had been reached to expand the city’s fringe. When Melbourne’s boundary was updated, it instantly increased the city’s population tally by tens of thousands of residents.
When comparing the two cities’ populations using the updated boundaries, Melbourne first leapt ahead of Sydney in 2018.
Before now, the closest Melbourne had come to parity was in 1930, when Sydney had 1.2 million residents compared with 995,000 in Melbourne.
Sydney overtook Melbourne as Australia’s most populous city in 1905, and has held the title since.
Demographers have been quick to point out that the counting measure used doesn’t paint a full picture of population trends in the country of about 26.1 million people.
The other main population classifications used, Greater Sydney and Greater Melbourne, still have Sydney at 5,259,800, ahead of Melbourne at 4,976,200.
This is because the boundary of Greater Sydney takes in the sprawling central coast region of the state of New South Wales where many residents commute to Sydney each day.
But Greater Melbourne has long been predicted to overtake Greater Sydney, and is estimated to take the crown of Australia’s most populous city on that measure by 2031-32.
Liz Allen, a demographer at the Australian National University, said Melbourne’s population had been growing faster than Sydney’s in recent decades due to its appeal to international migrants as well as Australians living in other states.
“Melbourne has an air to it that diversity seems to be celebrated more,” Allen said, noting recent overseas migration from India to Melbourne had led to a strong community which in turn has established the city as a preferable destination for migrants from the subcontinent.
Melbourne’s cheaper cost of living, particularly for housing, makes the city stand out from Sydney as a more attractive place to live given both cities’ educational and employment opportunities are largely on par, Allen said.
“Melbourne has established a pull factor, and we’ll continue to see it grow for some time,” she said.
