Single Transferable Vote

This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.

Single transferable vote is built to solve a problem that simple plurality voting cannot: how to elect several representatives from one district while still making sure that a voter's ballot counts for something even when their first choice candidate has no realistic chance, or already has more support than needed. Under STV, voters rank candidates in order of preference rather than choosing just one. A candidate who reaches a set quota of first preference votes, the minimum share of the vote mathematically guaranteed to fill a seat, is elected outright, and any votes that candidate received beyond that quota, the surplus, are transferred onward to the voters' next preferences rather than being wasted on a candidate who already won. If no candidate reaches the quota, the lowest performing candidate is eliminated instead, and their votes transfer to whichever remaining candidate each ballot ranked next. The counting repeats, electing or eliminating one candidate at a time, until every seat in the district is filled. The effect is a form of proportional representation without party lists: rather than voters choosing a party and the party choosing its representatives, STV lets voters rank individual candidates, including candidates from the same party, directly against one another, while still tending to produce a result where the overall spread of seats roughly matches the spread of voter preferences. The system is used today to elect the national parliaments of Ireland and Malta, the Australian Senate and the state parliament of Tasmania, and local elections in Scotland and a number of American cities, each adopting some variant of the same underlying counting method.

This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.

The single transferable vote was not invented once. It was invented independently, within a few years of each other, by people working in different countries who had never coordinated with one another, a genuine case of parallel discovery rather than one idea spreading outward from a single source. In Denmark, the mathematician and politician Carl Andrae devised a proportional counting method in 1856 and had it adopted for elections to the Danish Rigsraad that same year, introducing the specific innovation of numbered ballots, so that a vote's lower preferences could be recorded and counted without requiring voters to return for a second round. In England, the barrister Thomas Hare arrived at a strikingly similar system independently, publishing it in 1857 in a book called The Machinery of Representation, and his formulation became the version that spread through the English speaking world, eventually adopted by the Proportional Representation Society, later renamed the Electoral Reform Society, in 1884. The two systems were not identical. Hare's original quota, the minimum vote share needed to win a seat, set the bar in a way that could leave seats unfilled in some circumstances, a flaw the barrister Henry Droop corrected mathematically in the 1860s with what is now called the Droop quota, the version almost every STV election in use today actually applies. An even earlier partial precursor exists too: in 1819, a schoolmaster named Thomas Wright Hill used a rudimentary quota and vote transfer system to elect a committee for a literary society in Birmingham, decades before either Andrae or Hare took up the problem in earnest. Three names, three countries, and no evidence any of the earlier inventors knew of the others' work before it was already done.