It has been 10 years since the U.S. government approved the merger of Delta Air Lines and Northwest Airlines, creating a carrier that today is the most profitable in the world.

To celebrate Monday’s anniversary, Delta threw parties at its headquarters in Atlanta and in the Twin Cities, the hometown of the now bygone Northwest.

Hundreds of local employees gathered in a hangar at Minneapolis-St. Paul International Airport for the celebration and were connected to their colleagues in Georgia via a big-screen, live broadcast.

“Today is about the clear recognition that both airlines brought something special into the merger,” said Bill Lentsch, who ran the MSP hub for Northwest a decade ago and is now executive vice president of flying operations for Delta.

Touting the success of the marriage, Delta noted in 2008, before acquiring Northwest, it lost $503 million in adjusted pretax profit. Last year, the airline reported a $5.3 billion adjusted pretax profit.

“I think it’s been, without question, the most successful airline merger in history,” Delta Chief Executive Ed Bastian said during a summer interview in Minneapolis. “We’ve been able to pull them together and unify to a point that … with our crews and staff, you can’t distinguish between who was Northwest and who was Delta.”

At Monday’s event, Bastian recalled the global economy was rapidly decelerating as the merger closed and that the combined company suddenly had to contend with weaker demand.

“Ten years ago, we closed on our most audacious undertaking,” Bastian said at the party in Atlanta, seen on the screen at MSP. “We also did it at the very bottom of the worst economic downturn in our lifetime.”

Eagan-based Northwest was known for its aggressive growth strategies and business acumen while Delta had a reputation for good customer service. “The single most impactful thing Northwest brought to [Delta] was operational discipline,” Lentsch said, referring to metrics in on-time performance and baggage handling that provided an example for the merged company.

In Minnesota, Lentsch became the face of the merger, testifying to legislative committees and meetings of the Metropolitan Airports Commission, which operates MSP, as details were hammered out in 2007 and 2008.

At the time, Lentsch assured anxious Minnesota officials that Delta would maintain a sizable presence and employee base in the state. “Did I think it ever would’ve turned out this good? Probably not,” he said, “I thought there was a chance.”

With Northwest subsumed within Delta, Minneapolis-St. Paul lost the prestige and highest-paying jobs associated with a corporate headquarters. Still, Delta kept its promise of employing 10,000 people in the Twin Cities, although the makeup of those jobs is different. Northwest’s local payroll was about 11,500.

“Delta stood true to its commitments,” said Lentsch, who still lives in the Twin Cities and commutes weekly to Delta’s Atlanta office.

The Northwest-Delta merger served as the first of three megamergers among U.S. airlines. United and Continental joined in 2010 and American and US Airways followed in 2013.

Dean Twite has been a ramp worker for Northwest and now Delta for the past 39 years. He was one of hundreds of employees at the event who lived through the merger and remembers a collective anxiousness over what the future might look like under the combined company.

“It was always a concern with the economy. It was uncertain; it was the unknown,” Twite said. “Everyone knew there would be layoffs.”

But Twite said, “Delta turned out to be the airline we hoped they would be. It was a really well-thought out transition. Looking back, it was a great thing and I was happy to be a part of it.”