NYC held a primary election for mayor. Here's why it will take weeks to know the official winner.

There was a primary election Tuesday in New York City. But it could be weeks before the Big Apple's 8 million residents learn who could become their next mayor.

Though only a primary election, determining the winner of the Democratic contest is crucial, for in heavily Democratic New York, the winner of the primary will almost certainly defeat the Republican challenger to succeed Bill de Blasio (D) as mayor.

What are the current results?

Eric Adams, the Brooklyn borough president and former New York Police Department captain, commanded nearly a 10-point lead on Election Day following in-person voting and nine days of early voting. Maya Wiley, former counsel to de Blasio, was second, while Kathryn Garcia, former commissioner of the NYC Sanitation Department, trailed in third.

With 84% of precincts reported, the results as of 10 a.m. Wednesday were:

• Eric Adams: 253,234 votes (31.7%)
• Maya Wiley: 177,722 (22.3%)
• Kathryn Garcia: 155, 812 (19.5%)
• Andrew Yang: 93,291 (11.7%)
• Scott M. Stringer: 40,244 (5%)
• Dianne Morales: 22,221 (2.8%)

However, recently enacted changes to the voting process in New York City means the winner will not be officially determined until sometime in July.

What the heck is going on?

Two policies are driving the election bottleneck: mail-in ballots and ranked-choice voting.

Because of the COVID-19 pandemic, election officials allowed all New Yorkers to vote by mail. Those absentee ballots will be accepted through June 29, a full week after Election Day, as long as they were cast by Election Day, according to WABC-TV. Counting those ballots delays the primary outcome, plus voters will have the chance to fix, or "cure," problems with their mail-in ballots.

The biggest obstacle to determining a winner is ranked-choice voting, which is being used in New York's local and special elections. For ranked-choice voting in New York City's mayoral primary, voters ranked up to five of the 13 candidates.

The New York Times explained how the process works:

Think of ranked-choice voting as voting in rounds: If a single candidate receives more than 50 percent of first-choice votes in the first round, then he or she wins, and that's the end of the race. If no one exceeds 50 percent of votes in the first round, the candidate in last place is eliminated, and all other candidates move on to the next round. All the votes for the eliminated candidate will be reallocated to whichever candidate those voters ranked second, and then the votes are retabulated. Then the candidate in last place after that will be eliminated.

In New York's primary, these rounds of elimination will continue until there are two candidates left — even if a candidate collects more than 50 percent of votes before the very end. The candidate with the most votes in the final round wins. In each round, when a candidate gets eliminated, his or her votes get redistributed to whoever was ranked next on the ballot.

As far as the timeline: Election officials will post the ranked-choice results from Election Day and early voting on June 29, then update the results on July 6 to include mail-in ballots. According to WABC, "If there are still uncounted or disputed ballots, the process will be run yet again on July 13, and every subsequent Tuesday until a winner can be declared."

That means the winner of the Democratic primary, then, will be determined three weeks after the election at the earliest, especially if absentee ballots and the ranked-choice system closes the gap between Adams, Wiley, and Garcia.

What about the Republican primary?

The winner of the Republican primary was declared Tuesday night: Curtis Sliwa defeated Fernando Mateo, 71.9% to 28.1%.