Mainers have just done something big for American democracy: they’ve voted to change how they vote.

More than 52% of voters said “yes” to Question 5, a ballot measure to adopt “ranked-choice” voting at all levels of office except the president—making Maine the first state in the nation to do so.

To understand why this is so monumental, it helps to get a handle on how the traditional voting system distorts election outcomes and political incentives.

In all but a few municipalities of the US, voters get to pick a single candidate; whichever candidate earns the most votes wins. This tends to be a generally fair way of doing things as long as there are two candidates. But what if you add a few more? While the winning candidate might have received the most votes, it’s still possible that a majority of voters (meaning, more than half) objected to that candidate more than they supported one of his or her competitors.

Donald Trump’s primaries run is instructive. As of March 15, after which his prime competitors started dropping out, Trump had won only a third of the popular vote. It’s no stretch to suppose that a majority of voters felt more strongly about opposing Trump than they cared whether the nominee was Ted Cruz, Marco Rubio, or John Kasich. This is why traditional voting is sometimes called “plurality voting”—the candidate with the biggest plurality of votes wins, even if a majority of voters don’t want him to.

Plurality voting encourages candidates to campaign in a way that many think isn’t so great for American democracy. Since the name of the game is turning out the most votes for you, candidates benefit from focusing on riling up their bases. Smearing one’s opponent is a good way of doing this, creating a negative election atmosphere. And because party bases tend to be more politically and ideologically extreme than the overall population, the system can benefit candidates with policies much more radical than those of the communities they purport to represent. Moderate candidates or those from non-mainstream parties might be better liked overall, but because they split each others’ votes, they seldom win.

The system Maine just voted for, ranked-choice voting, favors candidates who appeal to the most people—and not just their base. Instead of just picking a single candidate in a race, voters rank all of the candidates in order of their preference.

League of Women Voters of Maine A sample ranked-choice ballot.

The results are tallied. If no one wins a majority (i.e. 50.1%) in that first round, the candidates with the fewest votes is knocked out of the running. Anyone who picked that last-place candidate as their first choice then have their second choices counted up. If no candidate has earned a majority after the second round, again, the candidate who now has the fewest votes is eliminated. The cycle continues this way until a candidate emerges with a majority. (See our previous article on Question 5 for a hypothetical breakdown of how this might work in practice.)

Imagine a candidate who is the first choice of a more militant part of the electorate but whom all the other voters rank last. He could very likely win in an election that uses the traditional plurality system. But in a ranked-choice system, he would lose. This is particularly important in Maine, which has a vibrant tradition of third-party and independent candidates. It also has a track record of divisive politicians winning elections without earning a majority, most recently, Republican governor Paul LePage.

Maine’s vote on Question 5 means that starting in 2018, when ranked-choice voting goes into effect, it will be the first state to use the system for gubernatorial, state legislature, and nationwide office.

However, the methodology, which is also sometimes called “instant runoff,” is not without its downsides. Research on elections in San Francisco suggest there may be a short-term voter suppression effect as people struggle to figure out how to fill out the more complicated ballot. Still, Maine’s independent-streaked political culture should eventually make the state a fascinating test-case for ranked-choice voting’s potential to reduce spoiler effects and favor third-party candidates.