The latest ABS population figures for December 2019 were released yesterday, and they confirmed what we have suspected for some time. Victoria will gain a 39th seat at the next election, while Western Australia will lose its 16th seat and the Northern Territory (barring any legislative change) will revert to a single electorate.
In this post I will focus on how the addition of a 39th seat will likely shake up Victoria’s electoral map, including an interactive map showing each seat’s variation from quota. I will return on Monday with a similar analysis for Western Australia.
The Australian Electoral Commissioner is required to determine the entitlement of electorates in the House of Representatives for each state one year after the first sitting of the House, which this year will take place on July 3. The Commissioner uses the most up-to-date state population statistics, which will be the December 2019 data.
Victoria gained its 38th seat at the previous election, after holding steady at 37 seats for a long period of time. This means these electoral boundaries are relatively fresh. No seat is significantly out of line with the average. The most populous seat is 4.7% over the average (Ballarat) and the least populous is 5% below the average (Chisholm).
When you add a 39th seat, you lower the average seat size from 111,551 to 108,690. 30 of Victoria’s 38 seats are then at or above the average, with only a handful slightly below.
Every seat will have to be redrawn to create enough surplus voters to draw a new seat, and the impact will likely be statewide, but you can zoom out to the regions to get a sense of which areas will be hit hardest.
This table groups seats into four areas. I have split the state between Melbourne and rural Victoria, and then also split these areas into north-west and south-east.
|Region||Seats||Variance from new quota|
|North & West Victoria||8||38.4|
There are 15 seats in Melbourne to the south-east of the Yarra. These seats are only slightly over quota: collectively 13.2% of an extra seat across these 15 seats.
So these seats shouldn’t require too radical changes. The individual seats range from +5% (Macnamara) to -2.5% (Chisholm). Outside of Macnamara, no other seat is more than 3% over quota. This area includes the seven least populous seats in the state, and all but one of the seats under the new quota.
There is more population growth in seats in central and western Melbourne, but most of the surplus lies in rural seats. The ten Melbourne seats to the north-west of the Yarra are collectively 26.5% of a seat over quota.
Some of the most populous seats lie to the west of Melbourne: Ballarat, Corangamite, Wannon and Bendigo are all 5% or more over quota, with Mallee not far behind.
So it seems most likely that the 39th seat will be drawn somewhere on the north-western fringe of Melbourne, absorbing surplus voters from these north-western rural electorates and the north-western half of Melbourne.
There is a natural divide through Victoria that runs from Port Phillip Bay, along the Yarra and then up through the Alps. The north-west half of the state, stretching as far to the east as Indi, includes 18 seats (10 in Melbourne, 8 outside Melbourne). This region has 65% of an extra quota’s worth of electors.
The Commission will usually try to avoid drawing electorates which cross the boundary. It seems likely the Commission will bring the north-west closer to a full quota by returning those suburbs on the north side of the Yarra which were moved from Jagajaga to Menzies in the last redistribution. This won’t make up 35% of a seat, but it might be enough to then just average out the differences across each half of the state.
Finally, here is the interactive map which you can click on to see the quotas for each electorate. Red seats are 1% or more under quota. Green seats are 1% or more over quota. Pale yellow seats lay in between.