Travellers use kiosks to check in for flights on Southwest Airlines in Denver International Airport Tuesday, Nov. 26, 2024, in Denver. (AP Photo/David Zalubowski)

Travellers ride an escalator to the shuttle trains to the concourses in Denver International Airport Tuesday, Nov. 26, 2024, in Denver. (AP Photo/David Zalubowski)

Travelers wade through a long line to pass through the south security checkpoint in Denver International Airport Tuesday, Nov. 26, 2024, in Denver. (AP Photo/David Zalubowski)

A traveler chats with agents at the Southwest Airlines check-in counter in Denver International Airport Tuesday, Nov. 26, 2024, in Denver. (AP Photo/David Zalubowski)

People pass by a long line of taxicabs at Denver International Airport Tuesday, Nov. 26, 2024, in Denver. (AP Photo/David Zalubowski)

Travellers pass through the south security checkpoint in Denver International Airport Tuesday, Nov. 26, 2024, in Denver. (AP Photo/David Zalubowski)

A traveler walks to his gate at Miami International Airport, Tuesday, Nov. 26, 2024, in Miami. (AP Photo/Marta Lavandier)

Workers prepare a United Airlines jetliner for departure from a gate on the A concourse at Denver International Airport Tuesday, Nov. 26, 2024, in Denver. (AP Photo/David Zalubowski)

A traveler sleeps by carts of her belongings near the Southwest Airlines counter in Denver International Airport Tuesday, Nov. 26, 2024, in Denver. (AP Photo/David Zalubowski)