If approved by federal regulators, the new airline will be the world's largest and link to Pacific Rim routes that Delta alone doesn't have. The airline said in a written statement that Delta passengers will gain "global connectivity."

While Delta officials said they will keep all of their hubs, Salt Lake City International Airport's managers believe Utah is uniquely positioned to benefit. In fact, some believe the merger strengthens the case for airport expansion because Delta has no other hub to funnel Western flights.

"We think it bodes well for Salt Lake City and the state of Utah and will be a great opportunity for us to expand as a hub and give a lot better and more air service to our residents," Mayor Ralph Becker said.

"We look forward to working with now the largest airline in the world and are optimistic about the future," airport spokeswoman Barbara Gann said.

The new airline's size may give Salt Lake City a boost in international travel, Gann said. "Northwest has some Asian reach that we don't have right now."

"As long as they don't leave out Salt Lake, it looks like [the two airlines] are very compatible," said Ruth Radmall, a Bountiful resident who was at the airport Monday picking up a Mormon missionary from Kazakhstan. "They cover different areas pretty much."

Utah's ski industry, a major seasonal driver for air traffic, also could benefit from better links to more cities.

"We have two huge assets as a ski industry. One of them is the greatest snow on Earth and the second is . . . having the best access anywhere," said Ski Utah President Nathan Rafferty. Air connections to resorts in Colorado and California are strained, he said, but "here it's getting easier and easier."

The airport's master plan calls for phased construction of new concourses that are parallel instead of sticking out like spokes from the existing U-shaped terminal. The parallel construction is considered better for busy hubs because it allows planes to enter in one direction and leave in the other, easing traffic jams as planes back away from their gates. The concourses would be connected by an underground shuttle similar to trains at the Seattle-Tacoma and Atlanta airports.

The first step already is moving forward, with a plan this year to start dispersing the de-icing station to several locations by the runways. This both clears space for new concourse construction and puts de-icing nearer the take-off zones.

Next would come the western half of one of the two planned parallel concourses, possibly within five years, airport executive director Maureen Riley said. It would replace Concourse C, the overloaded spoke that currently serves smaller regional jets. Incremental gate construction over the next decade or two could include a smaller third parallel concourse if demand grows.

City and state officials have estimated that if all phases are built, the plan could cost $2 billion or more. That cost is borne by the airlines through passenger fees, requiring approval from the newly merged airline that accounts for nearly three-fourths of Salt Lake's traffic.

Becker said he believes airlines will back the plan because it will move their planes through the airport faster, and because Salt Lake is a low-cost airport where a bump in passenger fees wouldn't seem excessive. The airlines' per-passenger costs are $3.26, compared to $10.95 in Denver and $15.50 in San Francisco, he said.

Delta already has downsized its Dallas and Cincinnati hubs, potentially increasing the importance of Salt Lake's role, Riley said. Still, Riley said negotiations with the airlines are continuing and she could not say how quickly airport expansion might proceed.

The expansion plan already has strong interest from other airlines, City Councilman Carlton Christensen said. Even without hub expansion, passengers that start or end their trips in Salt Lake account for about half of all airport traffic.

"If anything [the merger] could put pressure on us to build it sooner rather than later," he said.

Merger could benefit Salt Lake City and airport

* Delta hub rank: 2nd, behind Atlanta, ahead of New York and Cincinnati.

* Delta flights: 594 daily, 75 weekly international.

* Delta passengers: 7.9 million in 2007, 71 percent of SLC traffic.

* Northwest flights: Six daily.

* Northwest passengers: 134,000 in 2007, 1.2 percent of SLC traffic.

* Total airport passengers: 22 million a year, 24th busiest airport in North America.