History and use of instant-runoff voting

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Instant-runoff voting (IRV) is a ranked voting method used in single-winner elections. IRV is also known outside the US as the alternative vote (AV) or preferential voting. IRV is known by different names in the various countries in which it is used. It is also known as the 'Alternative Vote', 'Ranked Choice Voting', and 'Preferential Voting', although IRV is only one of many ranked (or preferential) voting systems.

Today it is in use at the national level to elect the Australian House of Representatives, the National Parliament of Papua New Guinea, the President of Ireland and President of India. In Australia it is also used for elections to the legislative assemblies (lower houses) of all states and territories except Tasmania and the Australian Capital Territory, and for the Tasmanian Legislative Council (upper house).

IRV is also used in some municipal elections in Australia, the United States, United Kingdom and New Zealand. Because of its relationship to the Single Transferable Vote (STV) system, IRV is used for by-elections and elections with only a single winner (such as elections for the President of Ireland) in some jurisdictions that use STV for ordinary parliamentary elections, such as the Republic of Ireland and Scotland.

Instant-runoff voting is based on the Single Transferable Vote electoral system, developed by Hill in 1819, Hare in 1857, and Andrae in 1855. Unlike IRV, the Single Transferable Vote was designed as a form of proportional representation involving multi-seat constituencies, while IRV is a majoritarian method, where minority sentiment goes un-represented.

It is also known as Ware's method, after William Robert Ware, the founder of the schools of architecture at the Massachusetts Institute of Technology (MIT) and Columbia University,^[1][2] who, while describing the experience of holding a demonstration single transferable vote election in 1871, mentioned that a similar method could be used for single-winner elections.^[3][4]

IRV was adopted for the Australian House of Representatives in 1918 and has been used to elect the President of Ireland since the office came into being in 1937. It was introduced in Fiji in 1999 and in Papua New Guinea in 2007.

IRV in its true form (what was called Alternative Voting at the time) was first used in Australia in 1909.