Revelers smooched and cheered the famous ball drop in New York's Times Square as the largest New Year's Eve celebration in the U.S. ushered in 2011. Most tried to set aside concerns about the worldwide economic downturn as partiers from New Zealand to Asia to Europe toasted to hopes of a more prosperous year to come.
In New York, a sea of people stretching for blocks braved tight security and cool temperatures Friday night to take part in the storied Times Square New Year's celebration, first begun in 1904. Crowds counted down to midnight as the glowing 6-ton Waterford Crystal ball descended the flagpole at the top of One Times Square to mark the new year's arrival.
City authorities don't give crowd estimates.
Chris Tulloch, 48, a computer engineer who came from upstate New York with his wife Sherine to experience Times Square for the first time, said the celebration was a good start for the new year.
"The amount of people in the crowd, the friendships that we formed, made us realize so many people have the same hopes and dreams for 2011 as we do," he said.
New York was the city in the spotlight as it coped with the lingering effects of a debilitating Dec. 26 snowfall, which hadn't been entirely cleared even as visitors were arriving for the New Year's celebration. Security in Times Square was tighter than usual, eight months after a would-be terrorist attempted to detonate a car bomb there.
Wendell Belt, 42, a retail worker from Philadelphia, came to New York to celebrate in Times Square with family. But he said he couldn't look past the troubled economy and feared 2011 wouldn't be any better than 2010.
"If the jobs don't come back, if the economy doesn't improve, if so many people are still looking for work, then we'll just have another bad year," Belt said.
In Las Vegas, thousands braved temperatures that dipped into the low 30s to watch an eight-minute fireworks show launched from the roofs of seven casinos. Jay-Z and Coldplay counted down the clock with crowds watching on the marquee of the $3.9 billion Cosmopolitan of Las Vegas.
In Honolulu, President Barack Obama was expected to ring in 2011 with friendly competition at his family's annual New Year's Eve talent show. The White House kept keeping Obama's talent a closely guarded secret. Several friends and family members were to join the Obamas at their rented oceanfront home in Kailua.
In Santa Fe, New Mexico, Republican Susana Martinez formally became governor at the stroke of midnight, becoming the state's female chief executive. She replaced Bill Richardson.
More than 26,000 people turned out for a New Year's Eve rave at the Los Angeles Sports Arena. The police presence was strong to try to prevent drug and other problems sometimes associated with the music events.
Festivities began hours earlier in the South Pacific, as Australians and New Zealanders were among the first to celebrate at midnight. In New Zealand's Auckland, explosions of red, gold and white burst over the Sky Tower, while tens of thousands danced and sang in the streets below. In Christchurch, revelers shrugged off a minor 3.3 earthquake that struck just before 10 p.m.
Multicolored starbursts and gigantic sparklers lit the midnight sky over Sydney Harbor in a pyrotechnics show witnessed by some 1.5 million spectators.
"This has got to be the best place to be in the world tonight," Marc Wilson said.
In Europe, Greeks, Irish and Spaniards were partying through the night to help put a year of economic woe behind them.
As rain clouds cleared, around 50,000 people, many sporting large, brightly colored wigs, gathered in Madrid's central Puerta del Sol square to take part in Las Uvas, or The Grapes, a tradition in which people eat a grape for each of the 12 chimes of midnight.
2010 was a grim year for the European Union, with Greece and Ireland needing bailouts and countries such as Spain and Portugal finding themselves in financial trouble as well.
"Before, we used to go out, celebrate in a restaurant, but the last two years we have had to stay at home," said Madrid florist Ernestina Blasco, whose husband, a construction worker, is out of work.
In Greece, thousands of people spent the last day of 2010 standing in line at tax offices to pay their road tax or sign up for tax amnesty.
"We can see that the quality of life is being degraded every day," Athens resident Giorgos Karantzos said. "What can I say? I don't see the light at the end of the tunnel."
In Asia, thousands gathered along Hong Kong's Victoria Harbor to watch fireworks explode from the roofs of the city's most famous buildings.
In Vietnam's capital, Hanoi, an estimated 55,000 people packed a square in front of the city's elegant French colonial-style opera house for their first New Year's countdown blowout, complete with dizzying strobe lights and thumping techno music spun by international DJs.
Vietnamese typically save their biggest celebrations for Tet, the lunar new year that begins on Feb. 3. But in recent years, Western influence has started seeping into Vietnamese culture among teens, who have no memory of war or poverty and are eager to find a new reason to party.
At Japan's Zojoji temple in Tokyo, monks chanted and revelers marked the arrival of the new year by releasing silver balloons with notes inside. The temple's giant 15-ton bell rang in the background.
In Seoul, South Korea, more than 80,000 people celebrated by watching a traditional bell ringing ceremony and fireworks, while North Korea on Saturday welcomed the new year with a push for better ties with its neighbor, warning that war "will bring nothing but a nuclear holocaust."
At the stroke of midnight in Cuba, state television broadcast images of troops at Havana's Morro Castle fort firing 21 salvos of a cannon in honor of the 52d anniversary of former President Fidel Castro's 1959 revolution. The live broadcast from the fort was interspersed with images of Castro throughout his decades at the helm of the communist island and some of his brother and current president, Raul Castro. After the brief broadcast, state television resumed its string of holiday salsa programs as some Havana residents fired small firecrackers outside.
In Dubai, the world's tallest building was awash in fireworks from the base to its needle-like spire nearly a half-mile (828-meters) above. Sparkling silver rays shot out from the Burj Khalifa in a 10-minute display.
In France, police were on alert for terror attacks and for celebrations getting out of hand. Rampaging youths typically set fire to scores of vehicles on New Year's Eve. Interior Minister Brice Hortefeux said 53,820 police officers were mobilized, 6,000 more than usual.
France has been extra vigilant following threats from al-Qaida and the kidnapping of five French citizens in Niger.
In central London, an estimated quarter-million revelers saw in the new year as red, white and blue fireworks — the colors of the Union Jack — shot from around the London Eye, lighting up the sky over the River Thames.
Associated Press writers around the world contributed to this report.