REPORTER: This morning, the travel rush is in full swing as millions of Americans take to the roads and skies ahead of Memorial Day. - The volume of travel is increasing. And that just means America is back and booming. REPORTER: According to AAA, today is expected to be the busiest day for drivers, with more than 37 million people driving to their destination this weekend. That's a 6% increase from last year. And airports will be just as busy. - All the modes of transportation are close to 2019 or pre-pandemic numbers. The one that is actually bigger than pre-pandemic is air travel. REPORTER: Airlines are being tested once again. A potential shortage of air traffic controllers could cause a repeat of last year's travel chaos. It comes on the heels of a series of close calls on runways across the country. DISPATCHER: You shouldn't be on that runway. REPORTER: The most recent incident, two flights were forced to abort their landings in San Francisco after a Southwest Airlines plane taxied across the wrong runway. Still, officials say they are ready for the crowds. And TSA's new rules for PreCheck are expected to alleviate some of the delays on the ground. - Now teenagers who are on the same reservation with a parent can go through TSA PreCheck, ages 13 through 17. REPORTER: And even if you do have PreCheck, travel experts warn the waits could still be long. - Don't say to yourself, well, I have PreCheck or I have CLEAR. I can push it and not get to the airport quite as early. Those lines will likely be long, as well, because the secret's out. - Here's another tip to save time at the airport. Make sure you pack properly, because the secondary bag search in security can cause delays not only for you, but other passengers.