South Australia has a parliamentary system of government. This makes elections for the South Australian House of Assembly doubly important; voters are choosing both a representative for their local electoral district, and someone who will support or oppose the current government.
The idea of voting for a representative is straightforward, but running an election for the House of Assembly is a complicated process requiring an extensive body of administrative rules. This includes rules about who is eligible to vote and how the votes should be cast and counted. The table below gives a brief summary of the electoral systems used for the House of Assembly since 1890, and information on the number of electors on the roll (registered voters), the number of electors in contested seats, the number of voters who cast a ballot, the electoral turnout (the rate of voting in contested seats), and the rate of informal (invalid) voting.
Note that the South Australian Parliament is bicameral, the upper house being the South Australian Legislative Council. The Legislative Council has its own electoral rules which are not included in this summary; information on elections and representation for the South Australian Legislative Council has yet to be added to this database.
The summary information on this page has been compiled from records in the Australian Politics and Elections Database at the University of Western Australia. The individual records for each general election and period in office in South Australia -- available through this website -- include sources and references.