SA state redistribution – draft boundary analysis


screen-shot-2016-10-19-at-8-22-18-pmWhile we were all recovering from the federal election, South Australia was undergoing a redrawing of its state electoral map for the 2018 state election. The draft electoral map was released in mid-August, and I blogged about the underlying statistics driving the redistribution at the time.

It’s taken me some time to get back to this redistribution, what with the many territory elections, council elections and by-elections taking place following the federal election, but it’s now complete.

You can download the 2018 draft map here.

The last election produced a result of 23 Labor seats, 22 Liberal seats and two independents. One of those independents, Geoff Brock, sided with Labor to give them a governing majority, while the other independent, Bob Such, went on sick leave soon after the election and later died of cancer. During Such’s absence, former Liberal leader Martin Hamilton-Smith resigned from the party to join Labor’s cabinet. Labor subsequently won the Fisher by-election, giving them a majority in the House of Assembly.

The Electoral Districts Boundaries Commission is required by law to consider the party-political impact of the redistribution, with the aim of producing a result which will give a majority of seats to the party that wins a majority of the two-party-preferred vote. Despite this requirement, Labor won a majority in 2010 despite a Liberal vote majority after preferences, and achieved government again despite losing the vote in 2014.

In line with their mandate, the EDBC has redrawn the boundaries to boost the Liberal position. Assuming no change from the 2014 election vote which gave the Liberal Party 53% after preferences, the new electorates would give the Liberal Party 24 seats and Labor 22. The last seat, Frome, is drawn as notionally Liberal but is held by an independent. Theoretically this should mean that the Liberal Party should be able to win a majority with no change in their vote (assuming they can win back Hamilton-Smith’s seat), although this theory did not work at the last two elections.

45 electorates remain notionally held by the party that won them in 2014 (either at the general election or, in the case of Labor and the seat of Fisher, at the by-election). The other two seats are Elder, in southern Adelaide, and Mawson, which has moved from being a southern Adelaide seat into a regional electorate by stretching out to take in Kangaroo Island and the Fleurieu Peninsula. Both seats are held by Labor MPs but are now notional Liberal seats.

The following map shows the new electoral map. Click on each seat to see the post-redistribution margin, and who held the seat before the redistribution.

This map is only a draft – we should be expecting a final version of the map to be released in November.

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  1. Ben – Is this SA the only state where the electoral commission has to take account of the Liberal/Labor “balance” in this way? And if SA took on the same system as the ACT, what would be the likely outcome?

  2. Even with the redistribution I can see NXT picking up enough seats to deny a Liberal Majority, and the Liberals will inevitably use “majority or nothing” rhetoric throughout the election campaign and give Labor another term in government.

  3. Jack: Such a considerable change would involve a complete redistribution into multi-member electorates and in close electorates the last seat is likely to be quite close, so it’s impossible to say with any certainty. However, I imagine that with, say, 9 five-member electorates the overall seat totals would be more likely to be closer to the statewide vote totals than the current single-member electorates.

  4. Interesting redistribution, some sensible changes but some boundaries, particularly around my end of town in the northeastern suburbs, are just plain bizarre. Seats like King and Newland have no rational community of interest and are clearly drawn to conform to the frankly idiotic “fairness provisions”. As much as the SA Liberals like to whinge about boundaries, they can’t escape the fact that they were simply outcampaigned in marginal seats all over Adelaide.

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