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Since 1970, the South Australian House of Assembly (the "lower house") has consisted of 47 single-member electoral districts consisting of approximately the same number of enrolled voters. The district boundaries are regulated by the State Electoral Office, according to the requirements of the South Australian Constitution and are subject to mandatory redistributions by the State Electoral Office in order to respond to changing demographics.
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Boundary adjustments
Electoral boundaries are adjusted after each election. The primary consideration is to attempt to ensure that the party that obtains 50% or more of the overall vote at a general election is able to form a government. The number of electors in each district must be within 10% of the average at the time of the redistribution order. After these primary considerations, other issues are considered, including economic, social and regional communities of interest. Despite this elaborate and expensive process, the system is not particularly reliable; cases where the party forming government has received less than 50% of the two-party-preferred vote are not un-common, and have occurred in three of the last four elections.
While South Australia's total population is 1.7 million, Adelaide's population is 1.3 million − uniquely highly centralised, over 75% of the state's population resides in the metropolitan area and has 72% of seats (34 of 47) alongside a lack of comparatively sized rural population centres, therefore the metropolitan area tends to decide election outcomes. At the 2014 election for example, although the statewide two-party vote (2PP) was 47.0% Labor v 53.0% Liberal, the metropolitan area recorded a 2PP of 51.5% Labor v 48.5% Liberal.
Numbers of Electorates and Members
Since 1938, the South Australian House of Assembly has had single-member electoral districts. From 1938 to 1968 there were 39 districts. Since 1970 there have been 47 electoral districts. From 1857 to 1933, the number of districts varied between 12 (1912–1915) and 27 (1890–1901). Each district returned from 1-6 members.
Electoral Districts
This table gives the number of members returned by each electoral district at each election.
Abolished electoral districts
These electoral districts no longer exist: