Subway ceremony for New York's first Muslim mayor

"This is truly the honour and the privilege of a lifetime," Mamdani said in a brief speech on Thursday.

The private ceremony was administered by New York Attorney General Letitia James, a political ally, at the old City Hall station - one of the city's original subway stops that is known for its stunning arched ceilings.

In Mamdani's first remarks as mayor, he said the old subway station was a "testament to the importance of public transit to the vitality, the health and the legacy of our city" as he announced the appointment of his new Department of Transportation commissioner, Mike Flynn.

Mamdani will be sworn in again, in grander style, in a public ceremony at City Hall later on Thursday by Senator Bernie Sanders, one of the mayor's political heroes.

Mamdani now begins one of the most unrelenting jobs in American politics as one of the country's most-watched politicians.

In addition to being the city's first Muslim mayor, Mamdani is also its first of South Asian descent and the first to be born in Africa. At 34, Mamdani is also the city's youngest mayor in generations.

In a campaign that helped make "affordability" a buzzword across the political spectrum, the democratic socialist promised to bring transformative change with policies intended to lower the cost of living in one of the world's most expensive cities.

His platform included free child care, free buses, a rent freeze for about one million households, and a pilot of city-run grocery stores.

But he will also have to face other responsibilities: handling trash and snow and rats, while getting blamed for subway delays and potholes.

Mamdani was born in Kampala, Uganda, the son of filmmaker Mira Nair and Mahmood Mamdani, an academic and author. His family moved to New York City when he was seven years old, with Mamdani growing up in a post-9/11 city where Muslims didn't always feel welcome. He became an American citizen in 2018.

He worked on political campaigns for Democratic candidates in the city before seeking public office himself, winning a state Assembly seat in 2020 to represent a section of Queens.

Mamdani and his wife, Rama Duwaji, will depart their one-bedroom, rent-stabilised apartment in the outer borough to take up residence in the stately mayoral residence in Manhattan.

Mamdani inherits a city on the upswing, after years of slow recovery from the COVID-19 pandemic. Violent crime has dropped to pre-pandemic lows. Tourists are back. Unemployment, which soared during the pandemic years, is also back to pre-COVID levels.

Yet deep concerns remain about high prices and rising rents in the city.

He'll also have to deal with Republican President Donald Trump.

During the mayoral race, Trump threatened to withhold federal funding from the city if Mamdani won and mused about sending National Guard troops to the city.

But Trump surprised supporters and foes alike by inviting the Democrat to the White House for what ended up being a cordial meeting in November.

"I want him to do a great job and will help him do a great job," Trump said.

Still, tensions between the two leaders are almost certain to resurface given their deep policy disagreements, particularly over immigration.

Mamdani also faces scepticism and opposition from some members of the city's Jewish community over his criticisms of Israel's government.

The new mayor and his team have spent the weeks since his election victory preparing for the transition, surrounding Mamdani with seasoned hands who have worked inside or alongside city government.

That included persuading the city's police commissioner, Jessica Tisch, to remain in her position - a move that helped calm fears in the business community that the administration might be planning radical changes in policing strategy.