As of September 2022, 56 cities, counties, and states have RCV in place, reaching approximately 11 million voters. This includes 2 states, 1 county, and 53 cities. Military and overseas voters cast RCV ballots in federal runoff elections in 6 states (source).

43 jurisdictions used RCV in their most recent elections (source).

Ranked choice voting was approved by voters in Benton County, Oregon in November 2016 (source), (source).

Proportional RCV has been used in Cambridge, MA since 1941 (source), (source), (source). It is also used for municipal and local elections in Ireland (source), Northern Ireland (source), Scotland (source), and Malta (source), (source). Some cities and districts in New Zealand also use Proportional RCV (source), (source). Australians use it for national parliamentary elections (source).

More information about where Proportional RCV is used can be found (here).

Empirical studies of electoral and legislative data indicate that women receive better representation in multimember districts than in single-member districts (source),(source),(source). However, some studies find that this effect is small (source). A national advocacy organization, Represent Women, specifically advocates for multi-winner races and ranked choice voting to improve representation of women in elected office (source).

Modeling research based on Portland’s demographics indicates that an electoral system based on multi-winner districts and proportional ranked choice voting would achieve fairer representation for Portlanders of color than single-winner races do.

One study explores eight alternative election systems for Portland’s city council (source), (source). The modeling reveals that an electoral system with three large multi-member districts and ranked choice voting would yield a city council with demographics roughly proportional to those of Portland’s general population. However, simulations of “traditional [single-winner] districted systems with 5, 7 or 9-member councils” result in very little representation for Portlanders of color (source). In terms of the current at-large system, the authors of the study note that “even though the current City Council has three POC Commissioners…between 1985 and 2019 only one POC Commissioner was elected to the council (source)."

A policy analyst at Sightline Institute asserts that these “results apply to Portlanders who are in the minority for any number of reasons: small business owners, people who are dependent on transit, those who get around by bike, youth, or parents of school-age children” (source).

Another study uses statistical modeling to explore representation under theoretical proportional RCV electoral systems in other U.S. municipalities that currently have single member districts. Using locality-specific data on demographics, voter preferences, and number of council seats in each city, the authors find that “STV tends to project proportional or slightly higher representation for the relevant minority group in each case, while SMD [single member districts] varies widely in its effectiveness depending on local circumstances” (source).

Several studies describe inherent bias in winner-take-all plurality electoral systems, where the majority is over-represented in elected positions relative to their proportion of the voters (source), (source) (source):

One study examines whether single member districts improve representation over at-large voting in plurality systems. The authors find that the change to single member district elections improved representation when the minority population was large and residentially segregated. However, in areas where the minority population was more residentially dispersed or insufficiently large, the change from at-large to single-member districts had no impact, or in some cases, a negative impact on representation (source).

A report from the Washington State Institute for Public Policy explains how in elections for local offices in the U.S., the “bias in favor of the majority is often promoted by ‘at- large' electoral systems. Under this plan, any group that votes as a fairly organized block can (and often does) defeat all non-majority candidates running city-wide” (source).

A wide range of studies have sought to understand the impacts of Ranked Choice Voting on voter turnout. Many find that voters participate at higher levels in RCV electoral systems.

Within this literature, different studies point to different measurable or theoretical reasons for increased turnout, discussed below. However, some find no impact on turnout for certain demographic groups. We also found one author whose studies show a negative impact.

>> Several studies indicate that switching to ranked choice voting increases voter participation in local elections from 9.6% to as much as 270% (source), (source), (source), (source).

>> One study demonstrates that “RCV helps reduce the substantial drop in voter participation that commonly occurs between primary and runoff elections…[but] otherwise RCV does not appear to have a strong impact on voter turnout and ballot completion“ (source).

>> Another study finds that RCV has a positive effect on youth participation in elections, but no significant effect for older populations. The data implies that this is because young people are more likely to be contacted by candidates and campaigns under RCV systems than young people in plurality systems (source).

>> One author has published a couple of studies indicating that RCV has a negative effect on voter turnout in mayoral elections (source), (source). In the latter study, the author finds different impacts for different racial groups, claiming that while RCV led to decreased turnout among Black and White voters in San Francisco, it led to increased turnout among Asian voters.

Studies of democracies across the globe tend to find that voter participation is higher under proportional representation systems than under majority or plurality systems.

>> One study of over 500 national elections in 20 countries finds that mean voter turnout under proportional representation is 82.1% while it is 77.6% under majority systems with single-member districts (source).

>> Another study of 36 countries from 1990 to 2014 finds that “turnout is about 4 percentage points lower in plurality/majority systems with single-member districts” (source).

Studies indicate that most voters understand RCV elections and correctly fill out their ballots, using the full complement of available rankings (source).

Older voters may perceive RCV as difficult or complex (source), (source), (source), but that doesn’t necessarily translate to under-voting or improperly filled out ballots (source). The evidence is mixed on whether other demographic groups experience difficulty understanding RCV.

One study finds that after trying RCV for the first time, voters like it more than they originally thought they would (source).

This voting system would eliminate the May primary. The May primary has decided 66% of outcomes in Portland city council and mayoral races since 1970 (source), (source). By eliminating primary elections and moving them to the fall, when Oregon voters turn out in high numbers to participate in Presidential or Gubernatorial elections, overall voter participation in city council member elections will likely increase (source).

Under the new system, Portland city councilors would need more than 25% of the vote to be elected into one of three positions in each district during the November general election.

This 25% threshold may be higher than the current threshold to win in many races. That’s because candidates who win over 50% of the vote in Portland primary races are elected, even though voter turnout in primaries can be quite low—in the May 2022 primary, it was 37% (source). By contrast, voter turnout in the November 2020 general election was nearly 80% (source). That means that under our current system, candidates can be elected in the primaries with votes from only 18.5% of the electorate and 23% of voters who will later turnout for the November general election.

Examples:

When Dan Ryan won reelection in May 2022 by capturing 54.5% of the primary vote, his voters represented 20% of the total electorate (registered voters) and 25% of likely voters — those who voted in Portland’s 2020 general election (source).

A similar thing happens in run-off elections. In the 2020 primary, in which 53% of registered voters cast ballots, Dan Ryan and Loretta Smith combined captured just 35% of the vote. In other words, 18.7% of the electorate—and 23.5% of voters who turned out in November—chose who would go to the general election (source).

Several studies use national and international electoral data to explore the connection between incumbent advantage and different electoral systems. These studies demonstrate that electoral systems with multimember districts and proportional voting, such as Proportional RCV, give less power to incumbents than majoritarian plurality systems with single member districts do.

One study compares two decades of national electoral turnover data from 25 countries. The authors find that proportional representation systems experience much greater turnover in elected offices than majoritarian systems do. They show that the United States, which relies on a majoritarian voting system, has the highest incumbency return rate of the countries included in the study (source).

Two studies of Ireland’s Proportional RCV electoral system find that incumbency causes an 18 percentage point increase in the probability that a candidate will win reelection (source), (source). However, the authors note their estimate of incumbency advantage, while large, is lower than comparable studies from the U.S. that find incumbency advantages of 30% to 40% (source), (source), (source).

Another study uses elections data from 40 U.S. states to estimate the incumbency advantage in state legislative elections between 1970 - 1986. The authors find that while all electoral systems have an incumbency advantage, it has grown at a substantially lower rate in states using multimember districts than in states with single-member districts (this study is of multi-member districts, though not proportional ranked choice voting) (source).

Research indicates that proportional election systems benefit moderate and smaller parties, as well as female candidates. Several academic papers report that proportional ranked choice voting systems have a tendency to elevate centrist candidates who have broad appeal (source), (source), (source), (source).

These findings have led several authors have theorize on the “centripetal” nature of proportional representation systems, noting that they may be appropriate electoral systems in politically divided societies.

Research and survey data show that RCV has the potential to result in more positive campaigns. Candidates are more prone to collaborate in RCV systems than in first-past-the-post systems and less prone to engage in negative campaigning according to the following sources: (source), (source), (source), (source), (source).

The authors of one study report that their “surveys of voters indicate that people in cities using preferential voting were significantly more satisfied with the conduct of local campaigns than people in similar cities with plurality elections. People in cities with preferential voting were also less likely to view campaigns as negative, and less likely to respond that candidates were frequently criticizing each other” (source).

Another study uses campaign communications data to study campaign civility in RCV and plurality cities. The authors analyze newspaper articles for campaign tone and find that articles from RCV cities “have significantly more positive than negative words” (source).

Evidence shows that electoral systems characterized by multi-member districts and proportional ranked choice voting are less susceptible to gerrymandering than winner takes all single-member district systems.

A study of gerrymandering in 54 democracies between 2012 and 2015 finds that majoritarian systems have a higher average gerrymandering score than proportional representation systems. The researchers conclude that “majoritarian systems are more prone to gerrymandering than mixed-member and above all…Proportional Representation (PR) systems” (source).

A study from the College of Engineering at Cornell uses computer algorithms to compare single member district and multi-member district scenarios for the U.S. house of representatives (source), (source). The researchers find that, “In terms of both fairness and preserving how geographically close residents are to their representatives, the best option is three-member legislative districts in which voters rank their choices and the candidate with the most first-place votes is the winner; surplus votes are transferred to voters’ next preferences” (source).

We were unable to locate studies on electoral manipulation that use real-world elections data. However, some studies use computational modeling to show that proportional ranked choice voting (also known as “Single Transferable Vote”) electoral systems are harder to manipulate than other systems, including traditional majoritarian plurality systems (source), (source), (source), (source).

These studies model the computational challenge of identifying how to vote strategically (as an individual or coalition) in order to influence election outcomes in ways that benefit the manipulator. They generally find that it is computationally more difficult to identify ways to manipulate elections in proportional RCV systems than in plurality systems.

Note: Voter “manipulation” is typically defined as a misrepresentation of preferences in order to achieve one’s desired outcome.