An estimated 1 million revellers packed into New York's Times Square on Saturday amid heightened security measures for a New Year's Eve party that passed without incident - aside from a lip-synching gaffe by pop icon Mariah Carey.
Shortly before midnight, the city's famous Times Square Ball set off on its 43-metre journey down a specially designed flagpole, before coming to rest at midnight to signal the start of the new year.
New York City mayor Bill de Blasio and outgoing UN Secretary General Ban Ki-moon pressed the button to start the 5-ton crystal ball on its path.
Carey took to the stage to ring in the new year on the television special Dick Clark's New Year's Rockin' Eve, albeit with a botched performance.
Carey stopped lip-syncing in the middle of one of her songs and paced the stage due to what appeared to be technical difficulties.
"Shit happens," the singer later said on Twitter in response to the slip-up. "Here's to making more headlines in 2017."
Over 60 garbage trucks loaded with sand blocked entry points to the area, following last week's attack on a Berlin Christmas market, where 12 people were killed when a truck was driven into a crowd of people.
In addition to trucks and other security measures, close to 7,000 police officers were assigned to guard against crime and terrorism in the city, including any approaches over water or from the air.
Earlier, European cities had celebrated the arrival of 2017, also amid heightened security measures.
In London, a 12-minute firework show beside the River Thames was accompanied by music from recently deceased British pop icons David Bowie and George Michael, as well as US musician Prince.
Some 3,000 police were on duty in the centre of London, and armed police were also seen travelling on the city's trains.
In Paris, sub-zero temperatures did not stop tens of thousands of revellers from filling the city's Champs Elysees to enjoy a firework show at the Arc de Triomphe.
As a security precaution, large concrete barriers and police vehicles were used to block various entry points onto Paris' famous boulevarde.
Across France, nearly 100,000 police were on duty for the night.
Parties in cities across Germany also took place against a backdrop of heavy police presence and bolstered security measures.
A man was arrested for shouting "Bomb, bomb, bomb!" at Germany's largest New Year's party beside the Brandenburg Gate in Berlin.
Police did not see the funny side of the man's actions and charged him. "He is now celebrating #Welcome2017 with us," Berlin police wrote on Twitter.