Thousands of travelers were stranded at airports throughout the country after a winter storm barreled through most of the US before and during the holiday weekend.

According to data from Flight Aware, Southwest has already canceled more than 2,400 flights on Wednesday and over 1,500 on Thursday due to the weather. On Monday, Southwest canceled more than 3000 flights. Other airlines canceled more flights than Southwest did on Tuesday, with Alaska Airlines calling off 75 flights.

Southwest's delays this week have a lot to do with the way the airline has its flights set up.

Southwest uses a system called a "point-to-point" that allows planes to fly from one location to another. The advantages of point-to-point systems are that they can offer direct and more affordable flights because the destinations they stop at typically have less air traffic, but flight schedules can quickly fall apart once one route gets canceled.

United is one of the airlines that uses a hub and spoke system. This allows airlines to cancel flights to certain locations without affecting other routes, as well as have access to additional planes and flight crews without flying them in first, something Southwest can't do without causing a domino effect of cancellation for its other flights.

Southwest will operate at a third of its normal schedule.

Due to the storm, Southwest ends up with flight crews and airplanes that are out of place, and not in the cities that they need to be in to continue to run their operations.

Mark Duebner was the director of aviation at Dallas Love Field. Southwest's system is normally very efficient with no slack, but if the crew isn't positioned in the right spot, then that flight gets canceled It spirals downward very fast. A perfect storm is what it is.

Travelers will have to wait in line for two or more hours to rebook their flights because of the mass cancellation. A number of passengers are sleeping on airport floors because they don't have new flights until after the new year.

Major transit hubs like Denver International Airport, Chicago Midway International, and Las Vegas are hit with cancellation notices. Southwest will cover the costs of hotels, rental cars, and other airline tickets if customers don't want to rebook their flights, according to Ryan Green, the company's chief commercial officer.

Pete Buttigieg, the US Secretary of Transportation, responded to the catastrophe by saying he would have a statement tomorrow. The US Department of Transportation said on Monday that it was concerned about Southwest's "unacceptable rate of cancellation and delays and reports of lack of prompt customer service." Southwest needs to compensate passengers for the canceled flights, according to two senators.

Southwest CEO Bob Jordan says in a video posted to the company's website that he reached out to Buttigieg on Tuesday to discuss what the airline was doing to help customers. He apologized to travelers and employees and said that the company's network was difficult to manage. He said that after days of trying to operate as much of their full schedule as possible, they decided to reduce their flying. His full statement can be watched below.

Southwest is struggling with a staff shortage in some locations. A state of operational emergency was declared by the airline at the Denver airport. In a memo leaked to employees, Southwest Airlines says staff will need a doctor's note when calling out sick, and that it will use mandatory overtime to fire employees. Southwest denied that the callouts were part of a coordinated effort.

Southwest Airlines said in a statement that they were fully staffed and prepared for the approaching holiday weekend when the severe weather swept across the continent. We have decided to operate a reduced schedule for the next few days as we work to recover from the surgery.

Southwest has had operational issues before. Southwest was forced to cancel almost 3000 flights last October due to staffing shortages and severe weather. Mike Van de Ven, the former Southwest COO, told employees that the company has a very aggressive hiring plan but that it still isn't where they want to be. According to the Dallas Business Journal, Bob Jordan said during an investor day presentation that the company needed to upgrade its systems in order to eventually operate 6,000 flights per day.

Southwest CEO Bob Jordan's video has been added.