Twilight falls on the city of Melbourne in this photo, shot with a long exposure from Southbank across the Yarra River.
CNN  — 

Melbourne has overtaken Sydney to become Australia’s largest city by population — thanks to a technicality.

The borders of the city, which is the capital of the state of Victoria, have been redrawn to include the district of Melton, allowing Melbourne to leapfrog Sydney, CNN affiliate 9News reports.

The Australian government had projected that Melbourne's population would overtake Sydney's by 2031-32.

In its 2022 population statement, Australia’s federal government said Melbourne was projected to overtake Sydney as Australia’s largest city in just under 10 years’ time, in 2031-32.

But the newly recast Melbourne has a total of about 5.8 million residents, almost 19,000 more people than Sydney, 9News added.

Flinders Street Station is one of Melbourne's best-known landmarks.

“It’s because more people have been moving out of Sydney, going to other parts of Australia, than have been moving in the opposite direction. Whereas in the case of Melbourne, in some years more people have moved to Melbourne than have moved out,” Nick Parr, a professor of demography at Macquarie University, explained to Sydney radio station 2GB.

“But the projections show that Sydney’s population will continue to grow, and also the Melbourne population will continue to grow,” he said, adding that immigration will “compensate” for the effects of low birth rates in both cities.

Liz Allen, a demographer at the Australian National University, told CNN that Melbourne’s growth is largely due to international migration over the past decade, as well as internal migration from within Australia and a natural increase from births.

“Melbourne has become a highly attractive place among more recent waves of overseas migration to Australia, particularly among people born in India. Growing community networks pull subsequent new arrivals from India to the Melbourne area,” she explained in an email.

‘Storm in a tea cup’

However, Allen disputes Melbourne’s claim to the title, telling CNN that media reports identified a measure called the “Significant Urban Area classification” as the thing that tipped Melbourne’s population over the threshold.

But, she said, this geographic measure “tends to be less stable over time,” noting that “the more commonly used, and stable, standard geographic classification of greater capital city shows Sydney is still Australia’s most populous capital. At the current rate of population change, Melbourne will overtake Sydney to take out the top spot in the coming decade.”

“Australia loves a competition and the added beef to the Sydney versus Melbourne rivalry has excited many, but it’s all a bit of a storm in a tea cup,” Allen said.