TYPES OF RCV
There are two primary forms of ranked choice voting (RCV) in the United States: Single-winner RCV (to select a consensus candidate with broad support) and Proportional RCV (to fill multiple seats on a legislative body in proportion to the electorate).
Some American jurisdictions have adopted block-preferential voting (BPV) as an alternative approach to filling multiple seats using RCV. Bottoms-up RCV with percentage threshold was used by the Democratic Party in four states to assign delegates during the 2020 Presidential Primary as well. Proportional RCV, however, is considered best practice for filling multiple seats using RCV.
This page covers Single-winner RCV and Proportional RCV, the two primary forms of RCV in the U.S.
All RCV contests feature a ballot on which each voter ranks the candidates according to their preference. Once all ballots have been collected, election officials apply established tabulation rules to identify the winner or winners. To learn more about marking an RCV ballot, see How RCV Works.
SINGLE-WINNER RCV
Single-winner RCV is used to elect one seat, such as mayor, governor, or president. In a single-winner RCV contest, a candidate who receives more than half of the first choices wins, just like in any other election. However, if there is no majority winner after counting the first choices, the race is decided by an instant runoff.
The candidate with the fewest votes is eliminated, and voters who ranked that candidate as their first choice will have their votes transferred to their next choice. This process continues until a candidate receives more than half of the votes in a round of counting.
The example below shows how single-winner RCV tabulation works.
Voters' first choices are counted. If a candidate receives more than half of the first choices (50% + 1), that candidate wins. However, if there is no majority winner after counting the first choices, the race continues to another round of counting.
In this scenario above, no candidate earned a majority of the vote.
The candidate with the fewest votes is eliminated, and voters who ranked that candidate as their first choice will have their votes transferred to their next choice. This process continues until a candidate receives a majority of the votes in a round of counting. Also known as instant-runoff voting (IRV).
In the scenario above, Candidate C has the fewest votes and is eliminated. Voters who ranked that candidate as their first choice will have their votes transferred to their next choice.
In the scenario above, Candidate C is eliminated, and voters who ranked Candidate C as their first choice have their votes transferred to their next choice.
Candidate A reached a majority and is declared the winner.
Single-winner RCV
Looking to learn more about ranked choice voting (RCV) when it is used to elect a candidate to a single office? Enjoy this quick video explainer to learn about the basics of single-winner RCV.
PROPORTIONAL RCV
Proportional RCV is considered best practice for filling multiple seats using RCV. It is used for a multi-winner contest, such as city council, when more than one individual is elected at-large or for district elections with multiple representatives. The voter experience is the same as single-winner RCV, where voters rank their choices in order of preference. First choices are then counted to determine if any candidates have enough votes to win, also known as the threshold. The threshold is determined based on the number of seats to be filled. Any candidate crossing the threshold is declared elected.
After the first round of counting, we can determine whether additional rounds of counting are needed to fill each seat up for election. If an elected candidate has a surplus – more votes than necessary to win – those votes are transferred to the next rankings on those ballots. In a round where no candidate crosses the threshold, the last-place candidate is eliminated, and their votes transfer to the next-ranked candidate on each ballot. This process continues until all of the seats are filled.
EXAMPLE: ELECTING 3 SEATS WITH RCV
When electing three candidates, the threshold would be 25% plus one vote. That is the smallest number of votes that guarantees that no more candidates can reach the threshold than the number of seats available to be filled.
