(Updates headline, first and second paragraphs)

WASHINGTON/CHICAGO, Nov 23 (Reuters) - More than 3 million airline passengers passed through U.S. airports over the weekend, disregarding calls to avoid Thanksgiving trips and making it the busiest air-travel weekend since coronavirus lockdowns hit in mid-March.

The Transportation Security Administration reported the traffic based on traveler numbers at airport security checkpoints.

The Centers for Disease Control and Prevention (CDC) on Thursday urged Americans not to travel during this week’s Thanksgiving holiday to mitigate the spread of the coronavirus as cases of COVID-19 spike around the United States.

For an interactive graphic tracking the global spread of COVID-19, open https://graphics.reuters.com/world-coronavirus-tracker-and-maps/ in an external browser.

U.S. airline executives last week said they had seen a rise in cancellations and slower bookings as COVID-19 cases increase, though Southwest Airlines Chief Executive Gary Kelly on Thursday said he still expected the month of November to be better for bookings than October and September.

While the TSA numbers show an improvement, screenings are still nearly 60% lower than at the same time last year.

Airlines are burning through millions of dollars every day as they wrestle with a sharp downturn in demand. But there have been pockets of improvement, and some carriers were hoping for upticks in travel around the Thanksgiving and winter holidays.

TSA screened 1.047 million passengers on Sunday -- the highest number of any day since mid-March, along with 984,369 on Saturday and 1.019 million on Friday.

There have been just three days since March 16 that the number of U.S. airline passengers screened topped 1 million.

Amtrak Chief Executive Bill Flynn told reporters Monday that demand at the passenger railroad for the Thanksiving travel period has "softened just a little bit over the last several days" to 20% of last year's demand, citing the CDC recommendation.

U.S. airlines say travel demand remains down 62% from a year ago, while international travel demand remains down more than 70%. Some officials think U.S. restrictions barring many non-U.S. citizens from arrival could be eliminated or reduced with new testing.

The CDC on Saturday said COVID-19 testing before and after international travel can reduce risk and "make travel safer by reducing spread on planes, in airports and at destinations."

On Wednesday, the chief executives of the seven largest U.S. airlines made a fresh plea for more payroll relief in a letter to congressional leaders.

American Airlines and United Airlines last month furloughed 32,000 workers.

The COVID-19 pandemic brought travel to a near halt earlier in the year, forcing airlines to scale back operations and seek government bailouts. (Reporting by David Shepardson in Washington and Tracy Rucinski in Chicago Editing by Andrea Ricci, Matthew Lewis and Cynthia Osterman)