From Sydney to Dubai, revelers welcomed 2014 with extravagant fireworks displays, while London prepared to celebrate by spraying clouds of fruit-flavored mist and Chicago and San Francisco planned massive outdoor festivities.
In New York, crowds gathered in Times Square for the annual New Year's Eve street party. By midnight, some one million people were expected to be on hand for Miley Cyrus, Melissa Etheridge and hip-hop artists Macklemore & Ryan Lewis and the dropping of the 11,875-pound, crystal-encrusted ball marking the start of the new year.
"We've been living on granola bars and little bottles of water because if you move, you lose your spot," said Sheila Harshbarger, who traveled to New York from Indiana with her daughter and staked out ground next to a row of police barricades in the freezing cold more than 14 hours before midnight.
In outer space, NASA astronauts will help ring in the new year by sending greetings to the Times Square crowd.
Astronaut Mike Massimino will bring a message from crew members on board the International Space Station orbiting the globe in a video display from space visible to those waiting for the ball drop.
There will be no crystal ball for Brasstown, in the mountains of North Carolina. At midnight it will hold its 20th New Year's Eve "possum drop" - in which a caged opossum is displayed in a Plexiglas container for spectators.
"If New York can drop a ball... then we can lower the opossum," organizers explained on their website.
The event got a last-minute go-ahead after a judge refused a plea by animal-rights group People for the Ethical Treatment of Animals to stop the event.
Across the northern United States, partygoers braced for snow and freezing temperatures. Chicago, which could see a significant snowstorm amid its flurry of festivities, was offering free rides on trains and buses from 10 p.m. to 4 a.m. to ensure revelers make it home safely.
In San Francisco, one of the last places in the world to see the clock strike midnight, some 200,000 people were expected to gather on the waterfront for a fireworks display illuminating the city's world-famous Golden Gate Bridge.
In other parts of the world, festivities were well under way.
At midnight in Sydney, Australia, a massive fireworks display lit up the sky around the city's famed Harbor Bridge and Opera House. New Year's organizers in Dubai were attempting to break the Guinness World Record for largest fireworks display.
In London, edible banana confetti and strawberry mist was set to rain from the sky as a fireworks display along the River Thames lights up Big Ben and other landmarks.
Across the United States, 2014 will also usher in political changes and the official start of a slate of new laws.
At midnight, New York City's next mayor, Bill de Blasio, will be sworn in at a private ceremony at his home in Brooklyn, succeeding Mayor Michael Bloomberg, who is leaving office after 12 years.
Former President Bill Clinton will deliver the oath of office for de Blasio at a formal inauguration ceremony on Wednesday at City Hall.
Americans who have signed up for new health-care coverage under President Barack Obama's Affordable Care Act are expected to begin receiving benefits on Jan. 1.
In Colorado, a new law will allow state residents to buy an ounce of marijuana at a time from specially regulated retailers.
Possession, cultivation and private personal consumption of marijuana by adults has already been legal in Colorado for more than a year.
"It will be like people waiting in line for tickets to a Pink Floyd concert," said Justin Jones, 39, owner of Dank Colorado in Denver, who has run a medical marijuana shop for four years and now has a recreational pot license.