A record number of passengers traveled through U.S. airports over Thanksgiving weekend, the Transportation Security Administration said Monday.

The TSA said it screened just over 2.9 million passengers on Sunday, surpassing the previous record of 2.88 million set on June 30. That was 10% more than the Sunday after Thanksgiving last year.

Travel was relatively smooth despite the crowds. On Sunday, just 55 flights within, into or out of the U.S. were cancelled, according to FlightAware, a tracking service. Nearly 8,000 flights were delayed, including several hundred that were impacted by snow in Denver and Chicago.

Airlines were eager to avoid the meltdowns that marred travel last December, when severe winter storms knocked out thousands of flights and left millions of passengers stranded.

Southwest, which canceled nearly 17,000 flights last year, said it purchased additional deicing trucks and updated its crew-scheduling technology. The airline was under particular scrutiny; the government recently threatened to fine Southwest for failing to provide enough help to passengers who were stranded last year.

The government also stepped up operations, hiring more air traffic controllers and opening new air routes along the East Coast ahead of the holiday travel season, U.S. Transportation Secretary Pete Buttigieg said last week.

Brett Snyder, president of the airline industry blog Cranky Flier, said Thanksgiving was a "remarkably good weekend for the country's airlines."

Between Tuesday and Sunday, no airlines canceled more than 1% of their flights, he said.

Snyder said airlines have figured out that they need to increase staff ahead of the holidays. But mild weather in most of the country also helped, he said.