Along with the first release from the 2021 Census, the ABS have released updated estimates for Australia’s states and territories and revised previous estimates for the last five years. These revisions shed new light on the stories we’ve been telling for state and territory populations.

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With the release of the Census results on June 28th, 2022, the ABS have also released updated population estimates for Australia’s states and territories. These quarterly estimates are up to December 2021, and show a return to some growth in Australia. The population at 31 December 2021 was 25,766,605 people, an increase of 127,953 people (or 0.5%) from a year before. This is still a low rate of growth historically, but it has come back up from the historic lows of 6 months before, with borders starting to reopen around the end of the year and net overseas migration back to almost zero. (We’re not losing more people overseas than are coming in any more.) The natural increase rate was also a bit higher, with more than 310,000 births and 171,000 deaths for the year.

Here’s how it plays out at a state level.

State/Territory	Population December 2021	Annual change	Annual change %
New South Wales	8,095,430	+11,238	0.14%
Victoria	6,559,941	-3,524	-0.05%
Queensland	5,265,043	+73,689	1.42%
South Australia	1,806,599	+9,644	0.54%
Western Australia	2,762,234	+30,505	1.12%
Tasmania	569,827	+4,270	0.76%
Northern Territory	249,345	+182	0.07%
ACT	453,324	+1,893	0.42%
Australia	25,766,605	+127,953	0.50%

So for the calendar year 2021, Victoria is the only state with a population decline. This decline is much smaller than previous, actually increasing in the final quarter of the year as lockdown restrictions eased. The lion’s share of Australia’s population growth remains in WA and Queensland, the only states seeing higher than 1% growth.

Previous population estimates have been revised against the new Census data

This isn’t the whole story, though. This release of quarterly population is the first one to feature rebased Census 2021 estimates. The Census has many uses, one of the key ones being ensuring the accuracy of annual and quarterly population estimates. While these estimates are not Census data in themselves, they do use the Census figures as a basis. And every Census, the past 5 years of population estimate data are revised by re-adjusted numbers using the Census as a baseline and post-enumeration survey to work out how many people were missed. The process for this is shown on the ABS website.

So everything from September Quarter 2021 back to September Quarter 2017 has been adjusted and will now differ from the figures we’ve reported on most quarters for the past few years!

The adjustments are benchmarked for the June quarter 2021 at the state level and here is what it looks like for the states and territories.

State/Territory	Population June 2021 (preliminary unrebased)	Population June 2021 (Census rebased)	Difference
New South Wales	8,188,651	8,093,815	-94,836
Victoria	6,649,066	6,548,040	-101,026
Queensland	5,221,233	5,217,653	-3,580
South Australia	1,773,396	1,803,192	29,796
Western Australia	2,682,257	2,749,864	67,607
Tasmania	541,315	567,909	26,594
Northern Territory	245,909	249,200	3,291
ACT	431,611	453,558	21,947
Australia	25,738,142	25,688,079	-50,063

Vic and NSW revised down

Overall, Australia’s population had been overestimated by around 50,000 people prior to the Census. But this difference was much greater at a state level. Both NSW and Victoria had been overestimated by about 100,000 people each. Victoria’s population had been declining, and has now also been revised downwards for many previous quarters.

Looking back through the previous data, this is not largely an overestimate due to extra losses from the lockdowns. The overestimating of Victoria’s population was already a sizeable 75,000 by December 2019, so ABS clearly thinks that they had overestimated the previous strong growth of Victoria’s population in the 3 years prior to COVID.

QLD unchanged

Queensland’s population they got almost exactly right, with very little adjustment. The state has been the fastest growing for several years.

WA, ACT, SA and Tas revised up

Western Australia has had a big revision upwards in population. It looks like the ABS didn’t previously factor in the effect of a highly mobile population who move towards the latest mining boom. This is the biggest upward numerical revision, over 67,000 more people in WA than was previously thought, or about 2.5% higher.

The largest adjustments in percentage terms are for Tasmania and the ACT, both underestimated by over 20,000 in populations of around half a million.

Reading through the notes on these adjustments, it appears that the trend of young people leaving Tasmania for the mainland was halted during the pandemic and many more stayed in the island state, bumping up the population (which wasn’t registered in the previous population modelling). This may also go some way to explaining the housing crisis faced by Tasmania. The revision is frankly enormous in a state that size. Tasmania’s population has just added a the equivalent of a city the size of Devonport (its 3rd largest city) more than we thought over the past 5 years. Population growth over 5 years was previously thought to be 4.3%, and is now 9.2%, more than double!

South Australia is another state with a big upward revision. The Census “found” an extra 30,000 people there, lifting their 5-year growth from 3.3% to 5.0%, largely due to stronger than expected interstate migration during COVID.

As with previous Censuses, these population revisions are quite significant, and underscore the importance of running a Census whose number one aim is to get a better understanding of the distribution of population for electorates.

Revising population estimates for local geographies

These revisions will flow through to smaller areas, including Local Government Areas, SA2s and suburbs as well. The June 2021 data for population estimates currently on our community (profile.id) sites is still un-rebased, and will be superseded by new data which is due for release on July 26th 2022. We’ll get that into the sites soon after it’s released. The state and territory figures above can give you an idea of the likely revision for your area; generally LGAs in states with a revision upwards are likely to be revised upwards, and those with a downwards revision are also likely to fall. Remember that when it’s revised, the past years 2017–2020 will also be adjusted, as will the corresponding growth rates for those years as well. Watch this space!

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