The Voting Methods Team wants to solve problems such as vote splitting and good-but-less-well-known candidates being discouraged from running for office. Some voting methods we recommend include approval voting,STAR voting, instant-runoff voting (IRV, or regular single-winner Ranked Choice Voting), and a variety of methods that provide proportional representation, including single transferable vote (STV, or proportional multi-winner Ranked Choice Voting) and allocated score (proportional STAR voting).
It turns out that there are also voting methods we would not recommend. This article looks into some of those, and, in doing so, answers this question: what are we looking to avoid in a voting method?
For electing individual leaders/executives (mayor, county clerk, governor, etc.):
Plurality
How it works: Vote for exactly one candidate. Whoever gets the most votes wins. This is used almost everywhere in the US.
Drawbacks: It’s easy for two similar candidates to split the vote, causing both of them to lose to a candidate that either one would easily defeat head-to-head. When people vote strategically to rally behind a frontrunner and avoid vote splitting, it yields the two-party system. Plurality also punishes honest voters who prefer long-shot candidates, effectively ignoring their votes and sometimes leading to an unrepresentative outcome.
What is better: Approval voting is the simplest reform; when voters can vote for every candidate they like instead of just one, voters don’t have to choose between splitting the vote and not voting for their favorite. STAR voting and IRV are other options.
Plurality + Runoff
How it works: Vote for exactly one candidate in the first election. The two top vote-getters advance to a separate, later runoff (though some jurisdictions forgo the runoff if one candidate gets a majority of the vote). An example of plurality + runoff is the “jungle primary” system. Plurality + runoff is used to elect the mayor of Denver and played a prominent role in the 2020-21 election of Georgia’s US Senators.
Drawbacks: Vote splitting can still determine who makes it to the runoff. This possibility discourages people from running for office and incentivizes dishonest voting. Having two elections instead of one is also more expensive.
What is better: If a community wants two separate elections, then approval + runoff (as is used in St. Louis) will prevent vote splitting and wasted votes in the first round. Alternatively, STAR voting (Score Then Automatic Runoff) and IRV (instant-runoff voting) don’t require people to vote a second time.
Top-Two IRV
How it works: Rank the candidates. The two candidates with the most first-choice support advance to an instant runoff using the already-cast ballots. The winner is the runoff candidate who is preferred over the other on more ballots. This is used to elect the mayor of London (though voters are only allowed to rank two candidates) and was used in a North Carolina judicial election in 2010.
Drawbacks: This has all the weaknesses of plurality + runoff (aside from the cost of an additional election), notably allowing for vote splitting in the first round and therefore artificially deflating the support of candidates who aren’t seen as viable.
What is better: STAR voting and regular IRV choose the finalists in ways that eliminate or reduce vote splitting and which encourage supporting one’s favorite, albeit non-viable, candidates.
Plurality + Electoral College
How it works: Vote for exactly one candidate. The candidate in your region who gets the most votes receives all of your region’s electoral votes. The electoral votes determine who wins. Until this year, Mississippi used a plurality + electoral-college-type voting method to elect its governor. It is still used to elect the US president.
Drawbacks: While all of these other faulty voting methods have issues when there are three or more candidates, they work just fine when there are only two candidates. Not so with plurality + electoral college. In a two-way Electoral College race, if ⅔ of all voters support candidate A and ⅓ support candidate B, it is mathematically possible for candidate B to win. An Electoral College can result in some voters having a thousand times as much power as other voters and encourages candidates to cater to voters in a small number of swing regions while ignoring everyone else.
What is better: Any other voting method. ANY.
For electing multi-member bodies (e.g. city councils and Congress):
Single-winner districts (not actually a voting method)
How it works: Instead of having a single race with multiple winners, several races each elect one winner using any single-winner voting method. This is used for the House of Representatives and city councils that use ward systems.
Drawbacks: While this can yield more diverse representation when voters are primarily divided on the basis of geography, it fails to do so with an electorate that is regionally homogenous. (For example, Massachusetts doesn’t have a single Republican in its 9-member congressional delegation.) Many districts are dominated by incumbents, and voters can end up with no choice at all. This happened in every single one of Broomfield’s five districts in 2011. Single-winner districts also open the door to gerrymandering.
What is better: Proportional representation will also yield geographic diversity if voters want to be represented by someone who lives close to them. When a single at-large election would lead to an election with an impractical number of candidates, e.g. CA voters voting on all their 50+ members of the US House of Representatives, a region can be divided into smaller multi-winner districts which use voting methods that ensure proportional representation within each district. The US Fair Representation Act proposes exactly this solution.
Block Plurality
How it works: Vote for up to N candidates, where N is the number of seats to be filled. The N candidates with the most votes win. Boulder and Lafayette use this to elect their city councils.
Drawbacks: Suppose there are 5 seats to be filled and three factions: Faction A has the support of 42% of voters, faction B has the support of 38% of voters, and faction C has the support of 20%. It seems fairest to have two representatives from factions A and B and one from faction C (this is what we call “proportional representation”), but with block plurality you’re liable to end up with all five representatives being from faction A. As with single-winner plurality, voters are also hesitant to vote for good, less-viable candidates.
What is better: Anything that yields proportional representation, such as single transferable vote, sequential proportional approval voting, or allocated score.
Preferential Block Voting
How it works: Rank the candidates. The first winner is determined using instant runoff voting. Then each successive winner is determined using IRV with each of the previously eliminated candidates reinstated for the next “election.” This was piloted in 2019 in the Utah towns of Payson and Vineyard and was used in a dozen Utah municipalities in the recent 2021 elections.
Drawbacks: Like block plurality, preferential block voting does not yield proportional representation. In block plurality voting, a voter can at least strategically give more weight to certain candidates by voting for fewer candidates than allowed. In preferential block voting though, if you rank #1 a candidate who is never eliminated, but never wins, then your ballot is effectively wasted. Meanwhile, other voters’ rankings may help elect multiple candidates.
What is better: Single Transferable Vote uses the same ranked ballots and does yield proportional representation.
So what do we want from a voting method that the methods listed above fail to achieve?
Voters should be able to express their full preferences
Vote splitting shouldn’t decide an election
Good, but less-viable, candidates should be welcome to throw their hat into the ring
Voting honestly should be strategically optimal
Few wasted votes
Gerrymandering should be impossible or ineffective
All voters should have an equal voice
Minorities should see proportional representation, not be excluded by winner-take-all elections