Southwest, which was founded at Love Field in 1971 as a regional carrier, renewed efforts in 2004 to repeal the law.
Now the nation's fourth-largest carrier, Southwest found success over the years with a low-cost business model that focused on smaller, less-expensive airports that are closer to metropolitan centers.
That business model would be threatened, airline officials have said, if the airline tried to split operations between DFW and Love Field. Southwest would have to spend millions of dollars at DFW to create the infrastructure it already has at Love Field, where it operates about 120 flights a day.
Flying to DFW Airport also costs more per passenger than flying to Love Field, Chief Executive Gary Kelly has noted. The higher expenses and infrastructure costs would mean higher airfares, he said.
"We want to serve Love Field. It's efficient, it's here, it's our home base, and it fits us perfectly," he said. "Most businesses have the right to choose where they operate. I don't know why it would be any different for an airline."
Southwest -- whose ticker symbol is LUV -- also has said it would face a daunting task starting operations at DFW, where American operates about 900 flights a day.
Other airlines, such as America West, also have declined incentive packages to take over unused gates at DFW because of the size of American's operations there.
The three flights still will stop in St. Louis, but passengers will continue on the same plane.
The Bush administration has not taken a position on whether the law should be repealed, Mineta said, and Congress must decide whether to change it.
American Airlines, which provides nonstop flights between Omaha and Dallas-Fort Worth International Airport, opposes changes to the law.
A consultant hired by Dallas-Fort Worth International Airport says an expansion of nearby Love Field would lead to reduced flights and millions fewer passengers each year at DFW.