Two-round system

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The two-round system (TRS or 2RS) is a voting method used to elect a single winner. In the United States, it is often called a jungle or nonpartisan primary. The system is also called plurality-with-runoff, though this term is sometimes used to refer to the closely-related exhaustive ballot and ranked-choice runoff systems (which tend to produce very similar results).

In a two-round system, both rounds are held using choose-one voting, where the voter marks their favorite candidate. The two candidates with the most votes in the first round proceed to a second round, where all other candidates are excluded.^{[note 1]} The two-round system is widely used in the election of legislative bodies and directly elected presidents. It is closely related to other members of the plurality-runoff family of methods (including plurality voting, ranked-choice voting, and plurality-with-primaries).

The two-round system first emerged in France, and has since become the most common single-winner electoral system worldwide.^[1][2]

In the United States, the system is used to elect most public officials in Mississippi, Georgia, Louisiana, and along the West Coast. A de facto variant is also used in the rest of the country, where party primaries narrow the field to two-party system candidates who generally receive the overwhelming majority of votes.^[3]

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