Since 1970, the South Australian House of Assembly — the lower house of the Parliament of South Australia — 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 South Australian Electoral Districts Boundaries Commission in order to respond to changing demographics.

Electoral boundaries are adjusted after each election. The number of electors in each district must be within 10% of the average at the time of the redistribution order. Other issues that may be considered include economic, social and regional communities of interest.^[1] From 1990 to 2018, it was also a requirement that each redistribution attempt to ensure that the party that obtains 50% or more of the overall vote at a general election would be able to form a government; this requirement has since been repealed.

While South Australia's total population exceeds 1.7 million, Adelaide's population exceeds 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 is crucial in deciding election outcomes. At the 2014 election for example, although the statewide two-party vote (2PP) was 47.0% Labor vs. 53.0% Liberal, the metropolitan area recorded a 2PP of 51.5% Labor v 48.5% Liberal.^a

• Map of outer rural electoral districts showing results from the 2018 election.
• Map of metropolitan and inner rural electoral districts showing results from the 2018 election.
• Map of metropolitan electoral districts showing results from the 2018 election.

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.

This table gives the number of members returned by each electoral district at each election.

These electoral districts no longer exist:

• Members of the South Australian House of Assembly
• Divisions of the Australian House of Representatives

^a Metropolitan 2PP correctly calculated by adding raw metro 2PP vote numbers from the 34 metro seats, both Labor and Liberal, then dividing Labor's raw metro 2PP vote from the total, which revealed a Labor metropolitan 2PP of 51.54%.^[2][3][4]