When most Americans cast their ballots, their vote counts for one candidate a race. The person who gets more votes than any other competitor wins, even if they do not get a majority of votes.

But New York City could become the biggest city in the country to change this age-old system altogether. Starting 26 October, voters have the option of switching to ranked-choice voting (RCV). In this scenario, even if someone’s top-choice candidate fails to get enough votes, their vote can still count.

Advocates of RCV see it as an effective way to ensure a winning candidate has received a true majority of the electorate’s support. They argue that it may encourage candidates to run on platforms that appeal to a broader range of people, without any worry of splitting the vote. In an era when Donald Trump failed to win a majority of voters, this could change the way American politicians think of their campaigns.

Under RCV, voters can rank candidates, from one to four if there are four candidates, for example. If no candidate is the top choice of a majority of voters, an “instant runoff” takes place. The candidate with the fewest No 1 votes is eliminated, and their supporters’ votes will automatically go to whoever was listed as their second choice. The process continues until one candidate has a majority of the votes. Voters can opt out of ranking and vote for just one candidate.

“[It] makes our elections more fair. It helps voters hold politicians accountable to all communities, and it saves taxpayers money and voters time,” said Susan Lerner, executive director of Common Cause New York, a nonpartisan grassroots organization that led the push to get RCV on New York City’s ballot.

If implemented, RCV could address a problem that has long plagued New York City, which is that long lists of candidates will run for the same role. The last election for public advocate – first in line to succeed the mayor – had 17 candidates run. More candidates, despite giving voters multiple options, can lead to the “spoiler effect” – which happens when a vote is split between multiple candidates with similar ideologies, leading to a candidate with an opposing platform to win.

Maine voters saw that during the state’s 2010 gubernatorial race. Paul LePage, a member of the state’s conservative Tea Party movement (who has gone on to say that he was “Donald Trump before Donald Trump became popular”), was up against two other major candidates – an independent and a Democrat. LePage won with just over 38% of the vote – 61% of the electorate voted for other candidates.

“There was a political sensibility that said here’s this person who was never terribly popular, wins with two pluralities, extremely extemporaneous governor and candidate, and yet he wins,” said Amy Fried, political science department chair at the University of Maine.

Fried said many voters were upset that LePage won without a majority, which happened again during LePage’s re-election in 2014. Utilizing that anger, good government activists convinced voters that elections did not have to be that way. They introduced RCV to the electorate, a majority of which voted in support of the system during the state’s 2016 election.

RCV was used in Maine congressional races for the first time during the 2018 midterms, and it will be used for the state’s 2020 presidential general election.

In 2018, the system ended up having a huge impact on one US representative in the state. Democrat Jared Golden edged his Republican competitor, incumbent Bruce Poliquin, with RCV. Initially, Poliquin received 46.2% of the vote, while Golden got a close 45.5% of the electorate. The state announced that ranked-choice voting procedures would take place, and over a week later, Golden was announced the winner with get 50.5% of the vote with RCV, while Poliquin received 49.5% of the vote.

In response, Poliquin filed a lawsuit against the state, testing the constitutionality of RCV. The federal judge Lance Walker dismissed the case, saying that ranked-choice voting “actually encourages first amendment expression” by encouraging third-party and independents to participate in elections.

While RCV is relatively new to the US, it has been largely popular in places that have taken the system up. Australians use RCV to elect members of their House of Representatives, and the system has been used for local elections in Canada, New Zealand and Hong Kong.

Other cities in the US such as San Francisco, Minneapolis and Santa Fe have used RCV in their elections for years, but New York, a city of 8 million people, would still be the largest. The main challenge is getting voters used to a new system.

Lerner said that Common Cause and other advocacy organizations have been trying to educate New York voters on RCV by going to local events and asking people to rank their favorite ice-cream flavor or beer brands. If passed in New York, RCV will be used in local elections beginning in 2021.

“It’s not going to solve everything that people dislike about our election, but I think it is going to address some things that bother New York City voters,” Lerner said.