As the clock struck midnight in New York City, it ushered in the start of a new year — and a new mayor.
Zohran Mamdani, the 34-year-old socialist who delivered a thumping victory in November's mayoral election, was officially sworn in during a midnight ceremony held in a subway station.
"Our campaign was built around listening to the people of New York, and we will govern in the same way," Mr Mamdani wrote on X hours before the ceremony.
"Tomorrow, we get to work."
The private, underground oath was the first of two ceremonies planned to mark Mr Mamdani's swearing in, with a public block party outside City Hall expected to attract thousands.
Subway swearing-in
In New York, mayoral terms begin on January 1 after elections.
In a bid to avoid any ambiguity about who oversees America's most populous city, it has become something of a tradition to hold a small midnight swearing-in.
Mr Mamdani chose the Old City Hall subway stop as the site of his midnight oath.
The station was decommissioned in 1945 and is accessible only a few times a year through guided tours.
Although no longer in use, the station boasts stunning architecture featuring tiled arches.
According to Mr Mamdani's office, the station reflects his "commitment to the working people who keep our city running every day".
Mamdani said the station represented an era when New York invested in infrastructure meant to improve people's lives, an ambition he said his administration aimed to carry forward.
Mr Mamdani is the city's first Muslim mayor.
In the midnight ceremony, Mr Mamdani placed his hands on copies of the Koran as he took the oath of office, marking the first time a New York mayor had used Islam's holy text to be sworn in.
The Korans will also be used in the second swearing-in ceremony.
New York Attorney General Letitia James, a political ally and notable foe of President Donald Trump, administered the oath of office.
Grant Reeher, a Syracuse University political science professor, said Ms James's role in the swearing-in sent a message to core supporters that Mr Mamdani was "going to be independent of the president".
Block party to attract thousands
With the midnight swearing-in completed, attention now turns to the far more public ceremony.
On Thursday afternoon, local time, Mr Mamdani will be sworn in again, this time on the steps of City Hall.
Performing the swearing-in will be Democratic Senator Bernie Sanders, who Mr Mamdani considers one of his political heroes.
There will be opening remarks from US Representative Alexandria Ocasio-Cortez, another political ally and a fellow New Yorker.
The public swearing-in will be accompanied by a block party along a stretch of Broadway leading up to City Hall.
Thousands of people are expected to attend, with performances, music and interfaith elements to be included.
'New era' promised
Mr Mamdani's team has labelled his swearing-in the "inauguration of a new era".
He promised free buses and childcare, city-owned supermarkets and a four-year rent freeze on New York's 1 million rent-stabilised apartments.
Mr Mamdani inspired a record-breaking turnout of more than 2 million voters and took 50 per cent, nearly 10 points ahead of independent Andrew Cuomo and well ahead of Republican Curtis Sliwa.
Weeks after winning the mayoral election, Mr Mamdani was praised by Mr Trump during a meeting at the White House.
The US president initially threatened to cut funding to New York if Mr Mamdani was elected, but said he would cooperate with the new mayor to tackle the city's affordability issues.
"I think you're going to have, hopefully, a really great mayor," Mr Trump said.
"He has views that are a little out there, but who knows? We're going to see what works, and he's going to change also. We all change."
ABC/wires
