Zohran Mamdani Is Sworn In as Mayor of New York City

Zohran Mamdani, the left-leaning populist who deployed a mix of charm, social media savvy and an unyielding focus on affordability to catapult him to political stardom, was officially sworn in as mayor of New York City early Thursday, just after the New Year's Eve ball dropped in Times Square.

The ceremony, held underground at an abandoned showpiece of a subway station by City Hall, caps Mr. Mamdani's yearlong rise from obscure state lawmaker to international figure, embodying the hopes of New Yorkers and Americans across the country who were enthralled by his journey to becoming the city's first Muslim and first South Asian mayor.

Four minutes before midnight, Mr. Mamdani, 34; his wife, Rama Duwaji; and Letitia James, the state attorney general, disembarked from a No. 6 train into the grimy, dimly lit, and yet stunning subway station. They promptly took their places on the steps beneath a dramatic archway emblazoned with the words, "City Hall." And then they waited, a bit awkwardly, a bit jovially, for the arrival of the appointed hour.