Youth voter registration and turnout surged in New York City last year — but it remains to be seen if the boom that fueled Mayor Zohran Mamdani’s election will have staying power.

New voter registrations more than doubled in 2025’s municipal elections compared to 2021, with over 260,000 people registering for the first time last year — a number approaching what is typically seen in a presidential election year, according to an analysis released Thursday.

Voters under age 30 accounted for two-thirds of those registrations, the study by the Campaign Finance Board said.

Turnout for the city election reached its highest level in more than 50 years, with numbers not seen since the 1969 mayoral race.

“Voter turnout and registration in the 2025 election cycle hit historic highs, with voters registering at rates more commonly associated with presidential election years, and voters and candidates embracing ranked choice voting in ways we’ve never seen before. But there’s more we can do to make it as easy as possible for more New Yorkers to participate meaningfully in our elections,” said CFB executive director Paul Ryan.

About 42% of registered voters aged 18–29 turned out in the general election, nearly quadrupling their 11.1% participation rate in 2021 when Eric Adams was elected mayor.

The dramatic increase in the youth vote reduced the average voter age in the election from 55 to 50, the report noted.

One voter data expert compared the youth turnout for Mamdani to that of younger ballot-casters who flocked to the polls to elect Barack Obama president in 2008.

“It was truly remarkable. It was amazing,” data maven Jerry Skurnik, senior consultant with Engage Voters US, said of the youth vote in the mayor’s race.

“It’s a major reason why Mamdani won the mayoralty. He excited the young people.

He said most of the polls in the Democratic primary were off, showing ex-Gov. Andrew Cuomo in the lead for City Hall — because they underestimated the surge in the youth vote.

But Skurnik cautioned that younger voters didn’t turn out at the same rate for candidates other than Obama.

It’s unclear whether they will do so for Big Apple candidates other than Mamdani, a skillful communicator who connected with Gen-Z via social media and other outreach.

“It remains to be seen whether they will come out again,” Skurnick said.

A special election for a vacant state Senate seat in Manhattan on Tuesday showed that Mamdani can’t just snap his fingers and get his legion of followers to back his favored candidate.

The candidate he opted to endorse in that race, Lindsey Boylan, was soundly defeated in Tuesday’s special election by establishment candidate Carl Wilson.

Also, an analysis of the upcoming June 23 congressional Democratic primary in Manhattan District 12 to replace retiring Rep. Jerry Nadler predicts that older voters ages 50 and up — not the youth — will likely decide the outcome.

Gotham Polling & Analytics reported that Democrats 50 and over accounted for 72-74% of the party primary turnout on Manhattan’s East and West sides in 2018 and 2022.

The consulting group’s report claimed that the Mamdani phenomenon in turning out younger voters won’t be replicated in a more confined congressional race.

“The 2025 mayoral primary was a remarkable event: record turnout, unprecedented youth engagement, and a 50+ share that dipped below historical norms. But it was a mayoral primary — a different election type with different mobilization dynamics,” the Gotham analysis said.

“The historical record shows that when the next congressional primary follows a mayoral surge, the electorate reverts to its structural baseline [a higher share of older voters turning out].”