WA Federal Redistribution Prospects using Updated Enrolment Data

Last October, eagle eyed observers spotted that there was something wrong with enrolment projection data released by the Australian Electoral Commission (AEC). The data had been released as base data for redistributions in Victoria and Western Australia. Data for the NSW redistribution was not affected.

The same enrolment growth rate had been applied across both states down to local statistical area level. This was a ridiculous assumption. It turned out the Australian Bureau of Statistics (ABS) had provided the Australian Electoral Commission (AEC) with the wrong data.

In the last few days the has AEC released corrected enrolment projections with growth rates that vary across both states. This post examines how this new data will influence the redistribution in Western Australia. A second post, hopefully tomorrow, will run through a similar analysis for Victoria.

In a previous post I explained why the seat numbers by state are changing. Another post, now superseded by the post you are reading, looked at boundary change implications from last October’s initial release of incorrect enrolment projections.

What doesn’t change is that Western Australia is gaining a seat in the current redistribution, restoring the 16th seat removed three years ago. Population trends mean the new seat will be created in a different part of Perth than the previously abolished seat of Stirling.

In short, the projected enrolment data makes even clearer that WA’s new seat will be created in Perth’s east. The other 12 Perth seats will shuffle west towards the Indian Ocean. Current enrolment data, and last October’s incorrect projected enrolments, indicated that a Perth seat would need to cross the metropolitan boundary. The new projections remove this prospect meaning the redistribution will be largely confined to metropolitan Perth.

A Quick Recap of Redistribution Rules

Redistributions redraw boundaries to ensure that all electoral divisions have roughly the same enrolment. Quotas are set dividing the state enrolment by the number of divisions. There are two quotas, one based on current enrolment at the start of the redistribution on (9 August 2023), and a second based on projected enrolments, set for 24 March 2028.

Current enrolment in Western Australia is 1,816,126 and the quota for 16 seats is 113,508, around 8,000 electors fewer than for the current 15 seats. All 16 new divisions must be drawn with enrolments within 10% of this number. The 15 current electorates are between 2.9% and 9.3% over the quota so most seats will lose electors to accommodate the 16th seat.

Projected enrolment is 1,945,845, the projected quota is set at 121,615, again around 8,000 electors fewer than for 15 seats. The projected quota tolerance is tighter than for the current enrolment and all divisions must be within 3.5% of the quota.

Based on the newly released projected enrolments, all divisions are over quota, but only the regional seats of Forrest and O’Connor, and the northern Perth seat of Moore, are under the 3.5% permitted variation. Seven of the state’s 15 current divisions are between 8% and 13% over the projected quota.

The quota restrictions must be applied in drawing the boundaries, but within these limits the Redistribution Commissioners can take account of –

  • community of interests within proposed districts, including economic, social and regional interests
  • means of communication and travel within the proposed district
  • the physical features and area of the proposed district
  • the boundaries of existing districts

Current Divisional Enrolment and Variation

Western Australia is regaining a 16th seat seat lost in the 2020 apportionment. That loss was caused by slower population growth in the wind down of the mining construction boom. The latest 2023 apportionment takes account of the two year Covid19 immigration hiatus that altered population relativities between the states. WA has continued to grow thanks to interstate migration, while Victoria and NSW were cut off from the overseas migration tap that usually counteracts both state’s loss through internal migration.

The table below shows Western Australia’s 15 current divisions. The first three columns show district name, holding party and margin as well as projected enrolment for March 2028. The final three columns show the projected enrolment variation in vote and percentage, and also shows the projected enrolment growth rate for each current division.

Reflecting the discussion that follows, the table shows electorates split into three groups. These are three non-metropolitan divisions, while Perth seats have been split based on lying north or south of the Swan River. The Perth divisions are ordered running inland from coastal seats in line with how boundaries are normally drawn.

‘*’ indicates divisions gained by Labor at the 2022 election.

WA Divisions – Variation from 16-seat Quota
Projected Enrolment Variation Growth
Division Margin Enrolment Votes Percentage Rate %
Non-Metropolitan Divisions (Total 0.08 quotas over, growth rate +3.7%)
Durack LIB 4.3 127,659 +6,044 +5.0 +3.6
O’Connor LIB 7.0 123,236 +1,621 +1.3 +2.0
Forrest LIB 4.3 123,141 +1,526 +1.3 +5.6
Perth North of the Swan Divisions (Total 0.45 quotas over, growth rate +7.4%)
Curtin * IND 1.3 128,489 +6,874 +5.7 +6.5
Moore LIB 0.7 124,919 +3,304 +2.7 +3.7
Pearce * ALP 9.0 133,344 +11,729 +9.6 +11.8
Perth * ALP 14.8 131,959 +10,344 +8.5 +6.9
Cowan ALP 10.8 129,525 +7,910 +6.5 +4.4
Hasluck * ALP 6.0 136,470 +14,855 +12.2 +11.1
Perth South of the Swan Divisions (Total 0.47 quotas over, growth rate +8.6%)
Fremantle ALP 16.9 131,747 +10,132 +8.3 +9.8
Brand ALP 16.7 135,959 +14,344 +11.8 +10.9
Tangney * ALP 2.4 127,734 +6,119 +5.0 +3.9
Swan * ALP 8.8 132,227 +10,612 +8.7 +8.0
Burt ALP 15.2 127,708 +6,093 +5.0 +9.3
Canning LIB 3.6 131,728 +10,113 +8.3 +9.9

Changes to the Regional Divisions

The map below is dominated by the giant seats of Durack and O’Connor. This makes it hard to see variation in metropolitan divisions so a second map concentrating on Perth is set out down the page.

Both Forrest (+1.3%) and O'Connor (+1.3%) fit within the permitted variation from quota and need no boundary changes. Durack (+5.0%) is slightly over quota, but can be easily fixed by re-uniting the areas around Bullsbrook with a metropolitan seat. Unless there are good arguments to adjust the southern boundary of Canning, or an Ellenbrook based seat can't be drawn without slower growth rural areas being included, there seems little reason to change WA's non-metropolitan seats.

In submissions to the Redistribution Commissioners based on the original projected enrolment data, both the Labor and Liberal submissions suggested seats cross the metropolitan boundary. The Liberal submissions suggested uniting the Darling Range parts of Perth with the Avon Valley. Labor suggested extending Canning to Collie. Neither of these changes are required on the new projected enrolments. (I posted previously on the major party submissions.)

Changes to Perth Divisions

The map below shows the variations from quota for the 12 Perth divisions. If you hover/tap any of the divisions you can see their name and their variation from the new 16 seat quota. All 12 divisions are over quota but only Moore is within the permitted variation.

This map makes clear that all seats in inner-Perth are closer to quota, surrounded by a halo of over-quota outer suburban seats in Pearce, Hasluck, Canning and Brand.

It is very unusual for the Swan River to be crossed by electoral boundaries down river from Guilford, with the single exception of North Fremantle. The drawing of boundaries almost always begins at the Swan River's mouth, drawing Curtin and Fremantle before moving inland.

In total the six seats north of the Swan contain 6.45 quotas worth of voters, the six seats south 6.47 quotas. As seats contract towards the Indian Ocean while maintaining their connection with the Swan River, space and enrolments open up for the new seat to be in Eastern Perth.

Boundary changes for the three northern beachside seats look straight forward. Both Curtin (+5.7%) and Moore (+2.7%) require only minor changes. The northern seat of Pearce (+9.6%) needs to shed enrolment which will be achieved by moving voters into Cowan and/or Hasluck.

Adjustments to Pearce, Cowan (+6.5%) and Perth (+8.5%) will be achieved by shedding voters to Hasluck (+12.2%) which is already well over quota. Hasluck looks certain to contract towards the coast. It currently consists of the rapidly growing Ellenbrook area in the upper Swan Valley as well as the Perth's Darling Range suburbs. The new boundaries are likely to see Hasluck become an Ellenbrook and the Swan valley based seat with areas further east in the Darling Range forming part of a new seat.

South of the Swan, Fremantle (+8.3%) and Brand (+11.8%) must shed voters. There is a very clear boundary between the two seats suggesting both will lose eastern parts to Tangney (+5.0%), Burt (+5.0%) and Canning (+8.4%). These three seats along with Swan (+8.7%) look set to shift west leaving suburbs on their eastern edge to form part of the new seat along with the Darling Range suburbs.

The Labor Party submission suggested adopting the Kwinana Freeway as the eastern boundary of Brand, a proposal that could be extended to Fremantle. Using the freeway would be a corollary of the Mitchell Freeway being used as a boundary north of the Swan rather than local government boundaries.

The seat likely to see most change is Canning. As the above map shows, it covers suburbs in the Darling Range east or Armadale and also includes new estates south and south east of Armadale. In absorbing surpluses from other seats, Canning is most likely to shift further south in the metropolitan area, losing all areas in the Darling Range.

The above scenario suggest the Darling Range suburbs from Canning could be combined with similar hill suburbs from Hasluck. Numbers would be rounded out by the inclusion of suburbs such as Guildford, Forrestfield and areas nearer Gosnells.

If the new eastern Perth seat lack enough community of interest by being too elongated north-south, or lacking north-south road connections, the Redistribution Commissioners may choose to re-align others seats, but this would involve much greater transfers of voters between divisions. Commissioners tend to try and minimise the proportion of voters shifted between districts.

There are many ways that the boundaries can be drawn, but the key point to make about the redistribution in Perth is that the seats close to the Indian Ocean are likely to see the least change, with the rolling transfer of enrolments creating greater change further inland and leaving room for a new seat in Perth's east. With seats north and south of the Swan having in total around half a quota of extra voters each, the most logical set of new boundaries would combine the surpluses in a single seat.

On a final note, the drawing of boundaries and the naming of seats is not always done at the same time. It may be that the new Darling Range seat retains the name Hasluck and a new name is adopted for a seat based on Ellenbrook. The names are less important than the boundaries.

While political attention focuses on which seats are abolished or created, it is how the changes propagate across other divisions that is more important when it comes to assessing the political impact of a redistribution.

3 thoughts on “WA Federal Redistribution Prospects using Updated Enrolment Data”

  1. Antony, do you have a ballpark LIB/LAB margin for a prospective eastern Perth seat? I imagine Canning as well as many other sears could see significant political changes too. Cheers

    COMMENT: No. I have no idea where the boundaries will be, just a view on the general location. A Darling Range based seat will need to include suburbs below the escarpment but I don’t know which ones or how many.

    1. It will be A swan based seat I my opinion and most likely notionally labor

      COMMENT: As I explain in the post, Hasluck is likely to be the Swan based seat with a new seat taking the Darling Range end of Hasluck. That’s roughly what both the Labor and Liberal Party submissions have suggested.

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