Plurality Voting System

The plurality voting system is a single-winner voting system often used to elect executive officers or to elect members of a legislative assembly which is based on single-member constituencies. This voting method is also used in multi-member constituencies in what is referred to as an exhaustive counting system where one member is elected at a time and the process repeated until the number of vacancies is filled.

The most common system, used in Canada, the lower house (Lok Sabha) in India, the United Kingdom, and most elections in the United States, is simple plurality, first-past-the-post or winner-takes-all. In this voting system the single winner is the person with the most votes (plurality); there is no requirement that the winner gain an absolute majority of votes.

In some countries such as France (as well as in some jurisdictions of the United States, such as Louisiana and Georgia) the "two-ballot" or "runoff election" plurality system is used. In order to ensure the winner gains a majority of votes, two rounds of voting occur. If any candidate in the first round gains a majority of votes, then there is no second round. Otherwise, the two highest-voted candidates of the first round compete in a two-candidate second round or all candidates above a certain threshold in the first round compete in a two-, three- or four-candidate second round.

In political science, the use of the plurality voting system alongside multiple, single-winner constituencies to elect a multi-member body is often referred to as single-member district plurality or SMDP. Plurality voting is also variously referred to as winner-takes-all or relative/simple majority voting; however, these terms can also refer to elections for multiple winners in a particular constituency using bloc voting.