Just after noon on Thursday, the Maine Secretary of State’s Office declared Democrat Jared Golden winner of the 2nd Congressional District race based on ranked-choice voting results. Here is everything you need to know about the process and what led to this historic moment in Maine – and national – elections.

What is ranked-choice voting?

The ranked-choice process allows voters to cast ballots for their favorite candidate and rank other candidates in order of preference. Those rankings only come into play if no candidate wins more than 50 percent of the vote on the first count of ballots. The idea behind ranked-choice voting is to elect individuals with a majority vote rather than a plurality (the most votes).

How does it work?

If no one wins a majority after the first tally, election officials eliminate the last-place finisher from contention and redistribute that candidate’s votes based each voter’s second-choice ranking. This process continues – with non-viable candidates being eliminated from the bottom up and their votes reallocated – until someone hits the magic threshold of 50 percent plus one vote. And that person is the winner.

Why is Maine using the ranked-choice system?

Maine has a long history of independent and third-party candidates running for public office. As a result, Maine also has a long history of electing individuals with less than majority support because ballots often feature more than just two candidates. For instance, only one governor since 1986 – independent Angus King in 1998 – received more than 50 percent of the vote. As a result, supporters pushed for a ranked-choice system.

How did the switch to ranked-choice voting happen in Maine?

In November 2016, 52 percent of Maine voters approved a ballot question that called for using a ranked-choice system in elections for governor, Congress and the Legislature. That didn’t, however, end the debate or controversy.

Responding to a query from the Republican-controlled Maine Senate, the state’s Supreme Judicial Court issued an advisory opinion that the Maine Constitution dictates that general elections for governor and legislative seats must be decided by a “plurality” of votes, not a majority. However, the Constitution is silent on primary elections for those offices, as well as all elections for Congress. The Legislature then passed a law delaying the implementation of ranked-choice voting several years – and only then if voters amended the Constitution to address the concerns.

Undeterred, supporters of ranked-choice voting organized a “people’s veto” campaign to override the Legislature. An even wider margin of voters – 54 percent – approved that ballot question in June, clearing the way for the system’s use in congressional elections this month.

Is Maine the first to use ranked-choice voting?

Maine is the first state to use the system for statewide elections. But numerous cities across the country – including San Francisco and Portland, Maine’s largest city – already use the process for local elections. Variations of the system also are in place in Australia, Ireland and several other countries.

Is this election the first time it is being used at the state level in Maine?

No. Voters were able to rank their candidates during the June 12 primaries for the Democratic and Republican nominations for governor, one legislative race and the Democratic primary for the 2nd Congressional District. The system was put to the test for the first time in the seven-person Democratic gubernatorial primary, resulting in Attorney General Janet Mills – who is now Governor-elect Mills – winning the party nomination during the fourth tabulation.

Why is ranked-choice voting in play in the 2nd Congressional District race now?

None of the four candidates on the 2nd District ballot received more than 50 percent of the vote. Both incumbent Republican Rep. Bruce Poliquin and Democratic challenger Jared Golden received roughly 46 percent, according to unofficial election results. The two independents in the race, Tiffany Bond and William Hoar, received about 8 percent combined. The votes that initially went to Bond and Hoar were redistributed to Golden and Poliquin based on each voter’s rankings on their ballot. Golden emerged on top with 139,231 votes to 136,326 for Poliquin.

Wait, why is a federal judge involved?

Poliquin said he won the election “fair and square” by receiving the most votes on Nov. 6. On Tuesday, he filed suit in federal court in Bangor claiming the ranked-choice process violates the U.S. Constitution because it “sets a plurality vote as the qualification for election” to Congress. However, the U.S. Constitution never uses the word “plurality” or addresses the issue, but Poliquin’s attorneys seized on a decades-old federal case from New York for their interpretation.

Poliquin and the three other plaintiffs – all 2nd District voters – also claim that ranked-choice voting prevents individuals from casting an “effective vote,” or a knowledgeable one, and violates due process clauses of the Constitution.

Poliquin also sought to halt the ranked-choice balloting process underway in Augusta before the final tabulations, but the judge refused to stop the process Thursday morning that led to Golden’s victory.

So is it over now that the ranked-choice tabulations have been run?

Not necessarily. Poliquin’s campaign could request a hand recount, but must do so within five days of the final tabulation.

U.S. District Court Judge Lance Walker still could rule for Poliquin in the broader case, in which case … well, we’re not sure what he could do and what would happen afterward. The campaigns or intervenor groups could then appeal whatever Walker decides.

Finally, there’s the other constitutional issue. According to some observers, the U.S. Constitution states the U.S. House and the U.S. Senate are the final arbiters of who gets to serve in those chambers. Specifically, Article 1, Section 5 states that “Each House shall be the Judge of the Elections, Returns and Qualifications of its own Members.” So some people argue that the House – which will flip from Republican to Democratic control in January – could make the final call about whether it’ll be Congressman Poliquin or Congressman Golden in D.C.