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.

Youth voter turnout surged with Zohran Mamdani on the ballot. Luiz C.…