Delta Air Lines completed its $2.8 billion acquisition of Northwest Airlines (NWA) on Wednesday, turning two of America's most storied airlines into the world's biggest carrier. Delta and Northwest closed the deal just hours after the Justice Department said it had no antitrust objections. The company will keep Delta's name, Atlanta headquarters, and chief executive Richard Anderson, who used to run Northwest. 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 would carry more traffic than either Air France-KLM (currently the world's largest) or American Airlines, the biggest US carrier. But antitrust regulators rejected worries 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 US consumers and is not likely to substantially lessen competition.” It 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. Also Wednesday, an attorney for 28 air travelers who had sued to block the deal said the case had settled. The attorney, Joseph Alioto, declined to release terms of the settlement, which he said was worked out on Friday and finalized over the last 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. When Delta Air Lines Inc. and Northwest Airlines Corp. announced their deal in April, it was widely thought that they were looking for government approval before a new President took office. Shareholders approved the merger on Sept. 25. It was also expected to be the first of a wave of airline mergers. That never happened. Two of the most vociferously pro-merger airlines, UAL Corp.'s United and US Airways Group Inc., backed away from a potential deal in May. Before that, Continental Airlines Inc. had considered, but rejected, pursuing a deal with United.