Did you miss your flight? Get in line. You just might miss another.

The lines to get through Transportation Security Administration checkpoints in airports across the U.S. are getting longer-- and there’s no relief in sight.

On American Airlines alone, nearly 6,800 passengers missed their flights during peak spring break week—March 14 through 20-- because of long checkpoint lines. And with summer on the way, the airline predicts things will only get worse.

TSA officials are responsible for screening nearly 2 million passengers every day, plus 1.2 million checked bags and 4.4 million carry-on bags at nearly 440 airports.

"The lines at TSA checkpoints nationwide have become unacceptable," American spokesman Ross Feinstein said in a statement Wednesday. "The result: our customers are waiting in TSA lines greater than one hour.”

"As we approach spring and summer, we are concerned that these lines will grow even longer," Feinstein said.

But there are no easy solutions to the problem. The long lines are the result of a perfect storm: Seven percent more people are flying in the U.S. this year – the Department of Transportation expects 699 million people will board planes in 2016 – and, thanks to a cap ordered by a budget-concerned Congress, there are only 42,500 TSA officers to screen them.

That’s the lowest level in five years, 12 percent fewer than in 2011.

TSA officials say they, too, are dismayed by the long lines, but their hands are tied. They are responsible for screening nearly 2 million passengers every day, plus 1.2 million checked bags and 4.4 million carry-on bags at nearly 440 airports.

But there’s good reason for the scrutiny. This week alone, a man in West Virginia tried to bring a loaded gun in his luggage through a checkpoint. In separate incidents, men carrying loaded semi-automatic handguns were prevented from boarding flights in Norfolk, Va., and New York City. Meanwhile, airports everywhere have dramatically ramped up security in the wake of the terrorist attack that killed 16 people at Zaventem airport in Brussels.

“This is one of the highest-volume travel years we’ve ever seen,” TSA Administrator Peter Neffenger said last week. “That means we’re going to have lots of people moving through the airports.

“Get to the airports early, because even if I can move you efficiently through the line, you’re still going to find long lines there.”