London Breed became the first Black woman to be elected mayor of San Francisco last Wednesday.

“Whether you voted for me or not, as mayor, I will be your mayor too,” Breed told a cheering crowd outside City Hall Thursday during a brief news conference.

But odds are, most people voted for Breed—just not necessarily as their first choice.

San Francisco is one of only of four California cities (all located in the Bay area) to adopt ranked-choice or “instant-runoff” voting, which allows voters to rank as many candidates as they want in order of preference. When ballots are counted, if there is no majority, losing candidates are filtered out and their votes are redistributed to candidates still on the ballot until a winner is declared.

Breed defeated two other Democrats, both County Supervisor Jane Kim and former state Sen. Mark Leno, after it briefly appeared that Leno might win as a result of receiving a significant number of Kim’s runoff votes after Kim was eliminated. While it might sound strange, Kim and Leno both endorsed each other in the middle of the campaign cycle, asking voters to rank the other candidate as their second choice.

In response, the San Francisco Chronicle editorial board accused both Kim and Leno of trying to “game the system,” by endorsing each other. But both candidates were doing exactly as the ranked-choice system intends: supporting like-minded candidates in an effort to boost candidates closer to their own political positions and edge out candidates they believe are further away.

“No system is perfect, but look at all of the type of systems out there. With simple plurality someone could get elected with 35 percent,” Pedro Hernandez, deputy director of FairVote California, told Rewire.News. “What it comes down to is ranked-choice voting is one of the most fair election systems out there.“

Hernandez said that ranked choice reduces negative campaigning in that candidates are more active in trying to pursue the second choice vote instead of bashing their opponents. But while ranked-choice voting has been endorsed by the New York Times and the Washington Post, both editorial boards acknowledged that it is not a panacea for fixing the problems of the election system in the United States.

“The major limitation is that [ranked-choice voting] is complicated, and requires voters to know a lot and have a clear preference ordering between all candidates,” Vladimir Kogan, a professor of political science at Ohio State University, told Rewire.News.

Kogan said that there are actually two potential problems with ranked-choice voting: the potential for the system to be complicated for voters, and ballot exhaustion—where candidates can be elected with less than a majority of votes.

In San Francisco, that was exactly the case. Breed won with 46 percent of valid votes cast (115,977 votes), because 8.6 percent of voters (21,510 votes) did not rank Breed or Leno among their top three options, “exhausting” the ballots.

FairVote California takes their endorsement of the voting system a step further, suggesting that it not only creates fairer and more respectful election cycles, but that it can help elect more women and more candidates of color.

In May, FairVote released a report showing increased candidate diversity in the Bay Area following the adoption of ranked-choice voting, ostensibly leading to the election of Breed and others. While there is a lack of academic research to corroborate this as a national trend, David Campos, the chair of the San Francisco County Democrats, believes that ranked-choice voting helped him when he ran for the San Francisco Board of Supervisors.

“Myself and the other Latinx candidates didn’t have to back out of the race for fear of splitting the Latinx vote. We could have respectful differences of opinion over issues and policy, yet still be the second and third choices of voters, and our community could still be heard,” Campos wrote in a blog post, critiquing the Chronicle’s editorial. “We were not spoilers for each other, and the Latinx vote did not split among too many candidates.”

The so-called spoiler effect, when candidates with similar ideologies split the vote and allow a different—potentially more extreme candidate—to win, has lead many to advocate for ranked choice. This is most popularly associated with Al Gore’s 2000 presidential campaign when he lost the crucial state of Florida to President George W. Bush by 537 votes, but Green Party Candidate Ralph Nader received 97,421 votes.

More recently, advocates for ranked-choice voting point to Maine, where “Trump before Trump” Republican Gov. Paul LePage won with only 38 percent of the vote in 2010 when the two other candidates split the vote. In 2016, Maine approved a ranked-choice voting system of its own, with many advocates looking to avoid a repeat of 2010’s gubernatorial election. The state’s first test of ranked choice came last week, ending Wednesday after electing its first party nominees using the system and approving another referendum to keep the system.

While some voters in San Francisco might not have ranked another option due to misunderstanding the ballot system, Hernandez is unconcerned. He said that despite the exhausted ballots, the ranked-choice system is far superior to traditional runoffs, where there is historically a 30 percent drop in voter participation. For him and FairVote California, ranked-choice voting remains the solution if the goal is to diversify the candidate pool and elect more women of color.

“What we saw was an increase in women and people of color running,” he said. “We’re always doing more research, but one could compare the top-two election system in California and see a very male-dominated field.”