The announcement Wednesday marked a swift conclusion to the deal. Earlier in the day, the Justice Department granted antitrust approval, and a lawyer for 28 air travelers who had sued to block the deal said the parties had settled the case.

The new Delta will be headquartered in Atlanta, and Delta chief Richard Anderson will head the combined carrier, which will integrate over the next 18 months.

"Salt Lake is going to be a really important part of the network in the new Delta," said Ed Bastian, the airline's president and chief financial officer, during a conference call with reporters. "I think Salt Lake City in fact comes out as really one of the winners in this deal because [it] is now the westernmost hub in the U.S. for the world's largest airline."

Bastian said the combination of Delta and Northwest into one airline with global operations reaching into Europe and Asia, coupled with the success of Delta's new route from Salt Lake City International Airport to Paris, means Utah travelers will have far more flying options.

"We will go looking to build on that success in the future, whether that means Amsterdam, which is one of the Northwest hubs [in Europe], in conjunction with KLM, or looking at Tokyo down the road. So I think it's a great win for Salt Lake City," he said.

One Delta employee reacted emotionally after hearing federal regulators had approved the merger, which had been in the works since April.

"I'm actually a little overcome by being a flight attendant right now at this wonderful juncture. There are so many wonderful things we're going to do as an airline. The sky is open," said Cindy Hanks, a Salt Lake City-based attendant.

Delta executives said travelers will see no differences right away. New uniforms will be phased in next year, and Northwest's fleet with its signature red tail will be repainted over the next two years, the companies said.

''I will tell you from a customer perspective and a frequent-flier perspective, it is business as usual," Anderson said.

The combined airline will carry more traffic than either Air France-KLM (which had been the world's largest) or American Airlines, the biggest U.S. carrier. But antitrust regulators rejected concerns that the new Delta would hurt consumers or competition.

Federal regulators wrote in a statement that ''the proposed merger between Delta and Northwest is likely to produce substantial and credible efficiencies that will benefit U.S. consumers and is not likely to substantially lessen competition."

They noted that other carriers also offer flights on most of the routes where Delta and Northwest compete with each other. The Justice Department also said consumers should benefit from savings on expenses for airport operations, technology and suppliers. The companies have said they can cut $2 billion a year in expenses once they combine.

The decision caps a six-month Justice Department investigation, which was closed without objection to the deal from the department.

Paul Tanner, another Salt Lake City-based flight attendant, said he was pleased the merger was moving forward, but wasn't entirely certain that it would help the company, which has been hurt by record fuel prices and tough economic conditions.

"I don't have a problem with the merger itself. Maybe it's the one thing that will give us a step up in an industry that has already been hammered by fuel prices," Tanner said.

Also Wednesday, an attorney for 28 air travelers who had sued to block the deal said the case had been settled. The attorney, Joseph Alioto, declined to release terms of the settlement, which he said was worked out on Friday and finalized over the past few days.

Kevin Mitchell, chairman of the Business Travel Coalition, said the merger will mean higher fares and fewer connections between mid-size cities and business centers. He said he was concerned about an enlarged Delta and other possible airline combinations and joint ventures.

''A first priority of the new administration should be to reconsider the rationale behind antitrust-immunized alliances and the market power they can exercise to the detriment of consumers," said Mitchell, who testified before Congress in April against airline mergers.

- THE ASSOCIATED PRESS contributed to this report.