WASHINGTON (NewsNation Now) — Millions of Americans packed airports and planes over the weekend despite U.S. health experts urging people not to travel for Thanksgiving.

The U.S. Transportation Security Administration reported that more than 1 million people passed through airport screenings on Sunday, the highest number since the COVID-19 pandemic swept into the country in mid-March. It’s the second time in three days that passengers screened topped 1 million, according to TSA.

On Saturday, more than 980,000 people traveled through airport screenings.

The number of people flying for Thanksgiving is down by more than half from last year, according to the TSA’s data. But it comes as the number of coronavirus cases in the United States has surpassed 12 million, with the most recent million coming in less than a week, according to data compiled by Johns Hopkins University.

It also follows warnings from the Centers for Disease Control and Prevention, the U.S. surgeon general and the nation’s top infectious disease expert Dr. Anthony Fauci.

“I’m asking Americans, I’m begging you: hold on a little bit longer,” Surgeon General Jerome Adams told the ABC News show “Good Morning America” on Monday. “We want everyone to understand that these holiday celebrations can be superspreader events.”

States have tightened restrictions in the lead up to the holiday. California enacted a curfew over the weekend. Several days ago, Kansas’ governor issued a statewide mask mandate.

In Pennsylvania, Gov. Tom Wolf announced that no beer and liquor sales will be permitted at bars and restaurants on the night of Thanksgiving eve, NewsNation affiliate WTAJ reported.

But many travelers are convinced they can visit loved ones safely.

Laurie Pearcy, director of administration for a Minneapolis law firm, is flying to New Orleans to attend her daughter’s bridal shower and have a small Thanksgiving dinner with her son.

“I don’t want to unknowingly make anyone sick. But I also don’t want to miss this special event for my only daughter,” she said.

Stephen Browning, a retired executive from Tucson, Arizona, will be flying to Seattle for Thanksgiving with his sister. The celebration usually has up to 30 people, but this year only 10 are attending. Everyone was asked to get a coronavirus test beforehand.

Browning doesn’t plan on removing his mask to eat or drink on the flight.

“This is my first flight since December 2019, so yes, I have concerns,” he said. “But I think most airlines are acting responsibly now and enforcing masks on all flights.”

Last week, the CDC urged Americans not to travel or spend the holiday with people outside their household.

“There is so much community transmission all over the United States that the chances of you encountering somebody that has COVID-19 is actually very, very high, whether it’s on an airplane, at the airport or at a rest area,” said Dr. Syra Madad, an infectious-disease epidemiologist for New York City hospitals.

The nation’s top infectious-diseases expert, Dr. Anthony Fauci, told CBS’ “Face the Nation” that people at airports “are going to get us into even more trouble than we’re in right now.”

Josh Holman and his family were planning to fly to Lake Tahoe and spend Thanksgiving with his brother, who lives in San Francisco, and his parents, who live in North Dakota. But they scrapped those plans.

“I see it as my civic duty not to spread this virus further,” said Holman, an assistant county prosecutor who lives outside Detroit.

More people tend to drive than fly over Thanksgiving, but even car travel is expected to see a drop-off, according to AAA. Based on surveys in mid-October, the association was expecting 47.8 million people to drive to Thanksgiving gatherings, down 4% from last year. But AAA said the drop could prove to be even bigger, given the worsening crisis.

The Associated Press and Reuters contributed to this report. Reporting by Dee-Ann Durbin and David Koenig of the AP and Daniel Trotta of Reuters.