Silicon Valley--the heart of the Internet and technology revolution--ushered in the new year with equal parts revelry and relief, just as other regions around the country had done just hours earlier.
Massive celebrations were broadcast around the world from New York's Times Square and Washington's National Mall to London, Paris, Moscow, Berlin and other European cities as the clock passed midnight. As in other cities, San Francisco celebrated with a fireworks display in its downtown.
After revelers rang in the new year, a flood of U.S. companies, including banks, utilities, hospitals and telecommunications carriers, announced that they had weathered the Y2K bug without service interruptions. This included the big West Coast utilities, such as Pacific Gas & Electric and Southern California Edison, at least as of 1 a.m. PST.
MasterCard claimed it already had completed 17.5 million transactions just after midnight. Intelsat stated that its worldwide satellite network operated without a hitch.
While optimistic, U.S. government officials said it was too early to declare victory over the Y2K bug. The Clinton administration said fallout from the so-called Y2K glitch--or lack thereof--would not be fully known until next week.
"By sometime on Tuesday, we'll have a pretty good idea of where we are in the United States," John Koskinen, Clinton's top Y2K trouble-shooter, told reporters.
He said it would take an extra day or two after that "before we can start to close the books on Y2K for the world."
Some Web sites, such as the one for the Times Square celebration, slowed as large numbers of users logged on to the Internet. Others, however, were unaffected.
"In the 30 minutes since the Y2K has reached this area (on the West Coast), the Cisco.com Web site has averaged download times of 0.65 seconds, comparable to the pre-Y2K performance of this Web site," Keynote Systems said in an announcement at 12:30 a.m. PST. Keynote measures downloads for its customers.
In the United States, airlines and oil companies reported few, if any, Y2K-related problems.
"Aviation has reached the year 2000, and I am pleased to report to you and (Transportation) Secretary Rodney Slater that the nation's air-space system is up and running safely and efficiently," FAA administrator Jane Garvey reported in a conference call to President Clinton. She relayed the all-clear signal while flying aboard an American Airlines flight en route to Dallas.
Federal Aviation Administration officials broke out in applause just after the transition at the agency's air-traffic command center outside Washington in Herndon, Va., which tracks more than 2,400 planes.
The news was the first major Y2K announcement issued within the United States, where the witching hour is still a few hours away.
Royal Dutch/Shell said its oil and gas operations continued to function without incident as midnight came and went, according to Reuters.
Only two minor Y2K-related problems have been reported so far. A power plant in the Midwest experienced a date-related computer glitch today after passing midnight GMT, but electricity supply was not disrupted and the problem was fixed quickly, electric industry officials said.
A calendar clock coordinating generation and transmission systems jumped ahead 35 days at the plant, but was corrected in a few minutes and did not affect customers or disrupt power, said John Castagna, a spokesman for the Edison Electric Institute.
Nearly one-third of all U.S. electric utilities have their operations timed to GMT, which passed midnight at 7 p.m. EST.
The Midwest utility, which was not named, was the only facility timed to GMT to see any glitches, Castagna said.
Also, gamblers at three Delaware racetracks were bitten by the Y2K bug when slot-machines refused to take their bets, according to John Koskinen, President Clinton's top adviser on the Year 2000 computer rollover.
"The state of Delaware has advised that it did experience a Y2K problem with a small number of slot machines operated at the three racetracks," Koskinen told amused reporters.
Revelers celebrated the new year without interruption first in New Zealand. Hours after midnight, all 12 of the country's key utility sectors were reporting smooth sailing, officials said.
Australian officials were next to report that electricity, water and air-traffic systems were working fine after the date changed.
Some Web traffic monitoring firms reported slow Net traffic in China, Australia and New Zealand as users flocked online to check that connections were working. Although some ISPs are bracing for what they expect to be a surge on networks as the clock strikes midnight in North America, they say they do not anticipate widespread problems.
As the new year reached Europe, authorities in Moscow said the date change hadn't caused any problems. In the countdown to 2000, Russian and American military personnel had been working together to ensure prevention of a catastrophic nuclear accident.
The world has been watching closely as country by country rings in the new year to see if fears of the much-hyped millennium bug have been warranted. The so-called Year 2000, or Y2K, bug stems from an old programming shortcut that used only two digits to signify years, such as "76" for 1976. If computer systems were not modified, some could mistake the year 2000 for the year 1900 and shut down.
In recent months, some technology experts have begun to question whether the huge sums of money and resources that have been focused on Y2K were necessary.
"I think one of the questions you've begun to see surface a little around the edges is, 'well, has this all been hype'?" said John Koskinenen, President Clinton's top Y2K trouble-shooter, said in a press conference this afternoon.
According to Reuters, U.S. undersecretary of state Thomas Pickering said at a briefing at the White House Y2K Information Coordination Center: "We can report from the early information that we have received from our embassies and consulates and the other sources...that the initial reports thus far are positive and that operations are normal" in Australia, Fiji, New Zealand, Japan, South Korea and several Pacific island states.
Although the initial reports are good, the most crucial testing grounds in Europe and the United States have yet to weigh in.
"It is important to bear in mind that many financial management and information-processing systems will not be fully tested until the world opens for business on Monday, Jan. 3," White House Y2K trouble-shooter John Koskinen told Reuters.
A United Nations-sponsored Y2K clearinghouse said earlier this week that the full impact of the date change would not be known until at least the end of January.
Moreover, relief over the lack of immediate troubles has caused problems in and of itself. Phones in New Zealand and Japan have been largely unusable today as people rushed to alert loved ones that all was well.
News.com's Jeff Pelline, Beth Lipton Krigel, Mike Yamamoto and Erich Luening contributed to this report. Reuters also contributed.