The first Democrat to be elected mayor of New York City in more than 20 years, Bill De Blasio, has been sworn in.
Mr De Blasio takes over from billionaire Republican Michael Bloomberg.
The new mayor has promised to govern with a progressive agenda, and to narrow the gap between the rich and poor.
The BBC reports Mr de Blasio took the oath of office outside his home a few minutes into the new year, in line with tradition.
A grander inauguration ceremony will take place later at City Hall, with former US President Bill Clinton administering the oath of office.
He won November's election by a record margin, contrasting himself with the pro-business Bloomberg years which he said had created a "tale of two cities".
Mr Bloomberg is credited with leaving New York a safer, healthier and revitalised place after his 12 years in office. However, critics say his policies have widened the gap between rich and poor.
Mr de Blasio was joined by his wife Chirlane McCray and their two teenage children outside their home in Brooklyn for the oath of office administered by state attorney Eric Schneiderman.