Assuming the government serves out a more-or-less full term, the next federal election will be held under new boundaries in three states and one territory, the exceptions being New South Wales, Victoria, Western Australia and the Northern Territory. Queensland’s redistribution has been held up pending official confirmation that its population growth will not entitle it to a new seat, but the other three redistribution processes have reached their fruition over the past fortnight, barring the delicate question of nomenclature.
The finalised boundaries for South Australia cancel two of the changes from the proposed boundaries published in March, leaving only the transfer of 10% of Spence’s voters to its northern Adelaide neighbour Makin, and small transfers from Mayo to Boothby and Barker. The former have little impact on the substantial Labor margins in both of the affected seats, while the latter adds half-a-point to Rebekha Sharkie’s margin in Mayo. Beyond that, the regional and remote seat of Grey, which bears the name of a colonial governor, will become O’Donoghue, in honour of the late Aboriginal leader Lowitja O’Donoghue.
Tasmania’s redistribution is as radical as South Australia’s is conservative, and have an extra layer of interest in also serving as the boundaries for state elections (votes shares at state level have been calculated by Ben Raue). Where formerly Clark accommodated Hobart’s core and Franklin its south and east, the redistribution has made a hard boundary out of the Derwent River, causing Franklin — which has the proposed new name of Tongerlongeter (subject of a critical opinion piece by Tony Abbott in The Weekend Australian) — to lose the suburbs and periphery south of Hobart to Clark. Clark’s gains are balanced by transferring northern Hobart to what had previously been the largely rural electorate of Lyons, while Franklin extends up the state’s east coast as far as Bicheno, taking a large chunk of what had formerly been Lyons.
For all their scope, the impact of the changes appears remarkably modest in electoral terms. None of the changes I estimate in the Labor-versus-Liberal two-party margins reach a full percentage point, and One Nation, who would appear to be a competitive prospect in the state’s regional seats, has had minimal change to its primary vote shares. Losing a large chunk of the territory he has serviced since 2010 will not help Andrew Wilkie, but he likely remains safe: the transfer to Lyons (which accounts for 43% of the enrolment) is not his strongest territory, and future state independent Peter George scored 22.9% in the area being gained from Franklin, many of whom would doubtless vote for Wilkie.
The minimal changes arising from the Australian Capital Territory redistribution were covered in a post a fortnight ago. My own calculations for new margins and party vote shares are accounted for in very great detail in spreadsheets for South Australia, Tasmania and the Australian Capital Territory. Similar exercises can be found on the sites of Antony Green and Ben Raue.