TSA lines are so bad at some airports that United and Delta are letting passengers move their flights

Travelers in long lines at Atlanta's Hartsfield-Jackson International Airport on Monday.

Nathan Posner/Anadolu via Getty Images

• Houston and Atlanta airports are warning travelers of four-hour security lines.
• Delta, United, and Allegiant have waived some fees to give passengers rebooking flexibility.
• TSA agents have been calling out of work as they aren't being paid due to a government shutdown.

Some airlines are waiving change fees for passengers affected by hourslong waits at airport security.