MIAMI (NewsNation Now) — Airports in the U.S. are the busiest they have been since the pandemic started, and so are many COVID-19 testing locations nationwide.

Long lines and hours-long wait times were reported Monday in states including Florida, Illinois, and Texas.

Despite warnings from the Centers for Disease Control and Prevention not to travel, many Americans are masking up, and flying out to visit loved ones for Thanksgiving.

More than 1 million airline passengers went through TSA checkpoints nationwide Sunday. That’s the most since the pandemic began in March.

Many travelers feel safer getting a COVID test before traveling to holiday gatherings.

But doctors warn that a negative test result is not a fail safe way to protect yourself and others during the holidays.

It’s possible you could be exposed to the virus in the days leading up to a test, and it is not detectable yet.

Or you could still get COVID after you receive a test.

“Being tested is much better than not being tested. However, it does not guarantee by any means. Someone says okay I’m COVID negative, that means grandma can come over for Thanksgiving. I say no that is not what that means,” Dr. Olveen Carrasquillo with the University of Miami said.

If you are going to gather with family for Thanksgiving – experts urge you to keep the gathering small and socially distant.