For several years now, ranked-choice voting -- a system by which voters rank-order their selections of candidates rather than choosing just one -- has been bandied about by experts and politicians as a way to improve the voting process. While it's been used in mayoral elections in Minneapolis and San Francisco, the process hasn't really caught on widely. But could 2014 be the year it starts taking off?

Ranked-choice voting emerged as an alternative to the traditional American method of first-past-the-post voting, where whichever candidate gets the most votes wins the election.

By contrast, under ranked-choice voting, voters whose first-choice candidates finish at the bottom in the initial round have their vote added to the total of their second-choice candidate. If there is no winner after those votes are reassigned, then the lowest-finishing candidates' votes are reassigned until someone receives at least 50 percent of the vote.

The system is designed to produce a winner who is at least somewhat acceptable to the widest share of the voting population. Ranked-choice voting doesn't affect the result in a two-candidate race, but once three or more candidates are running, the system prevents the election of a winner who secures less than a majority of the vote.

An actual "runoff" -- in which the top two finishers face off against each other -- can achieve the same result. But ranked-choice voting makes the selection process quicker by making a second, or if necessary, a third round of voting almost instantaneous. It also avoids the likelihood that voter turnout will decrease in the runoff election. In fact, ranked-choice voting is sometimes called "instant-runoff voting."

By way of example, if ranked-choice voting had been used in the 2010 Maine gubernatorial race, conservative Republican Paul LePage probably would have lost. LePage won just 38 percent of the vote, barely edging out Independent Eliot Cutler with 37 percent; Democrat Libby Mitchell won 19 percent. Observers suspect that ranked-choice voting would have redistributed the lion's share of Mitchell's supporters to Cutler, providing him with more than enough support to win.

That certainly would have harmed the Republican candidate. But there are plenty of instances where a Democrat would suffer. Take the 2012 Montana Senate race, where Democrat Jon Tester won with less than 49 percent of the vote. Republican Denny Rehberg's 45 percent of the vote could easily have been combined with second-choice votes from supporters of a Libertarian Party candidate, enabling Rehberg to win.

Perhaps the most notable case in which ranked-choice voting could have made a difference was in Florida's 2000 presidential voting. If just a tiny fraction of Ralph Nader's 1 percent of the statewide vote had gone to Al Gore -- who was a more likely second-choice candidate for most Nader voters than George W. Bush was -- then Gore would have won Florida, and the presidency.

In the United States, ranked-choice voting has made tangible, though limited, inroads in recent years. In addition to Minneapolis and neighboring St. Paul, it's now used in San Francisco; Oakland, Calif.;Berkeley, Calif.; and Portland, Maine. A few states -- including Arkansas, Louisiana and South Carolina -- have allowed residents temporarily living overseas to cast votes by ranked-choice voting. Some smaller localities have adopted it as well, including San Leandro, Calif.; Takoma Park, Md.; and Telluride, Colo.

But Election Day 2013 will bring one of the highest-profile tests of the system in the United States, when voters in Minneapolis will use ranked-choice voting to choose from among three dozen candidates to fill an open mayoral seat. Meanwhile, other places being targeted for possible expansion of ranked-choice voting include New York City, Los Angeles and Maine (statewide).

In an important development, the nation's largest voting machine vendors are finally building ranked-choice-voting into their equipment, said Rob Richie, the executive director of FairVote, an electoral-reform advocacy group that has long supported ranked-choice voting. That makes it possible for advocates to focus "on what ranked-choice voting will accomplish, rather than what will be necessary to make it possible to administer," Richie said.

Ranked-choice voting is already used abroad. Irelanders use it to choose the president, Londoners vote by ranked-choice in the mayoral elections and, notably, Australians use it to elect members of parliament, a system that has been in place for almost a century.

Peter Fray, a veteran political journalist in Australia, said the system is broadly popular in his native country. "There are grumbles from time to time about the results it throws up, such as the Motoring Enthusiasts Party or far-right candidates winning," he said. "But faced with first-past-the-post, Aussies will go preferential any day of the week."

Advocates tout several benefits from the system, beyond electing candidates with the broadest degree of acceptance. "One of the biggest is that it saves a ton of money," said Steven Hill, the former director of the political reform program at the New America Foundation and a leader in the bid to expand ranked-choice voting to San Francisco in 2002. Cost, he said, can be especially problematic in cities that end up having to hold runoffs in both a primary and in a general election. "San Francisco, which pays approximately $4 million to administer a citywide election," Hill said, "has saved millions of dollars beyond the initial startup costs as a result of having fewer elections."

Higher voter turnout is another benefit, Hill said, since the final vote in municipal elections can be held on the same day as major statewide or national elections, when more voters are already casting ballots for higher offices.

Advocates add that the system encourages demographically diverse representation. Since beginning to use ranked-choice voting in 2004 for elections to its 11-member Board of Supervisors, San Francisco voters have more than doubled the number of racial and ethnic minority supervisors from four to nine, including five Asian Americans, two African Americans, and two Latinos. San Francisco elected its first Chinese-American mayor using the system, and in that race, the runner-up was Latino.

The reason for the expanded diversity is that minority voters may be able to select a minority candidate for first and second place; if one is eliminated, their lower-choice candidate may prevail instead.

To be sure, the system has also inspired opposition. For starters, it's more complicated for voters to understand, at least until they get used to it. In addition, some say there may be value in having an actual final round of campaigning between two candidates. That way, voters can see the top two finishers directly battling each other for public support.

These drawbacks have come into sharpest relief when second-place or even third-place finishers in the first round ended up winning the election. "That of course is to be expected, and is the reason to ask people to rank candidates," Richie said. "But it can catch some people by surprise if they don't understand the system."

In 2010, Oakland held its first election for mayor under a ranked-choice voting system. The frontrunner, Don Perata, was the first choice of about one-third of voters (including many in the political establishment), but most other voters put him at or near the bottom of their list. Perata ended up losing to city Councilmember Jean Quan, based on her stronger record of securing second place votes.

Quan's experience suggests that candidates running in ranked-choice voting contests should avoid polarizing appeals and instead emphasize broadly popular themes, which could ultimately inspire less acrimonious elections. "Quan's campaign and others in the Bay Area with ranked-choice voting suggest that earning second choices is best done through people meeting the candidate and coming to believe the candidates will listen to them," Richie said.

After Quan's victory, some members of the Oakland political establishment, seemingly craving the predictability of a more traditional voting system, sought to overturn the ranked-choice voting system. But the repeal effort stumbled.

Voters in the Bay Area have tended to be copacetic about ranked-choice voting, Hill said. "I don't think most San Franciscans even think that much about it. It's faded into the background, much like the operating system of your computer, which is not something you think about very much."

In Minneapolis, ranked-choice voting was used in 2009, but with popular incumbent R.T. Rybak running, the race wasn't competitive. This time, he isn't running for a new term, so the 2013 open-seat election has become a much higher-profile test of the system.

As Governing recently reported, City Councilmember Don Samuels and former City Council President Dan Cohen were tied at 16 percent in a September Minneapolis Star-Tribune poll, followed by two candidates with greater establishment support and money -- Councilmember Betsy Hodges with 14 percent and former Hennepin County Commissioner Mark Andrew at 10 percent. Each of these candidates except for Cohen are Democrats; Cohen is an Independent.

Ranked-choice voting "could have a big impact," said David Schultz, a political scientist at Hamline University in Minneapolis who has studied the city's electoral process. "It may affect campaign styles, in that it is hard to criticize a candidate and then ask his or her voters to make you their second choice."

Still, ranked-choice voting hasn't had staying power everywhere.

In Pierce County, Wash., voters approved ranked-choice voting in 2006, then used it in 2008, but later repealed it. Why? The answer probably has to do with the complicated trajectory of Washington state's primary system, said Todd Donovan, a Western Washington University political scientist.

"In early 2000s, the U.S. Supreme Court ruled our 'blanket' open primary unconstitutional, so the state was experimenting with a replacement," Donovan said. "During that period, Pierce County adopted ranked-choice voting, while the state used a different system for state races. When the Supreme Court upheld a 'top-two' primary system similar to the old blanket primary, it may have made it seem as if ranked-choice voting was no longer needed there, or it might have highlighted the fact that the county was using a different election system for state vs. local races."

Washington state's changing electoral processes may have contributed to the short life of ranked-choice voting in Vancouver, Wash., as well. "The voting system was adopted for Vancouver in 2003, and once I left the council, it had no champion," said Jim Moeller, a Democratic former Vancouver City Council member who is now Speaker Pro Tem in the state House. "It was never used, and since it required action by the council and county auditor, the legislative window closed."

The system has also been scrapped for statewide races in North Carolina. It had previously been available for certain judicial special elections.

Still, the biggest challenge to the further spread of ranked-choice voting may be that electoral reform remains a hard issue to rally rank-and-file voters around. "Voting reform is always a challenge," said Heather Gerken, a Yale Law School professor who studies election law. "People are skeptical of change, and politicians are often the most skeptical of change. No matter how good the idea, it's always an uphill slog to get it passed."

Correction: An earlier version of this article reported that San Francisco has elected one Latino to its Board of Supervisors since using ranked-choice voting. The correct number is two.