Every three years, approximately one year after the federal election, Australia’s population is assessed, and each state and territory is given a set number of seats to be filled in the next Parliament, based on population. When the number of seats allocated to a state changes, a redistribution is immediately triggered to draw up new electoral boundaries.
This time around, population shifts have guaranteed that New South Wales will lose its 48th seat, and Western Australia will gain a 16th seat. It now appears that the ACT’s population will not be sufficient to give them a third seat, after it first appeared to be possible in late 2013.
These redistributions will by necessity cause significant changes to borders, in order to create a whole new seat in WA and squeeze NSW’s populations into 47 seats.
Electorates will need to be drawn to be within two quotas. A quota is drawn up as the average population per electorate as of the time of the redistribution, and another one which is the average projected population of each new electorate as of 3.5 years after the conclusion of the redistribution. These quotas will be 1/47th of the NSW population, and 1/16th of the WA population.
Below the fold, I’ve posted my analysis of the likely trends in the NSW redistribution, and have produced an interactive map showing the population quotas in each electorate.
In short, I think the seat most likely to be abolished is Hunter, which will have significant knock-on effects in the Hunter region and in western NSW. Seats in inner Sydney will shift east, while seats throughout Western Sydney will expand in size in southwestern direction, shifting Werriwa and Macarthur further into the fringe of Sydney.
I’ll be back tomorrow with a similar analysis of the prospects in Western Australia.