That would top the June 23 mark of more than 2.99 million. American Airlines said Sunday is expected to be its busiest day of the entire summer; it plans more than 6,500 flights.
Federal officials expect air-travel records to fall as Americans turn the timing of July Fourth on a Thursday into a four-day -- or longer -- holiday weekend.
"This week we are expecting -- between now and Monday -- over 1 million passengers at" Los Angeles International Airport, said Justin Upshaw, an LAX spokesman. "We're expecting Sunday to be a very busy day as people return home from their Fourth of July holiday."
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Jacquelyn Brooks' flight was scheduled to depart at 7:30 a.m. Wednesday. "And so we left at 4 (a.m.), got here right on time," the Palmdale resident said. "If you don't go right at that window, you're not going to make it."
AAA forecasts that 70.9 million people will travel at least 50 miles from home over a nine-day stretch that began June 27, a 5% increase over the comparable period around the Fourth of July last year. Most of those people will drive, and the motor club says traffic will be the worst between 2 p.m. and 7 p.m. most days.
TSA was created after the terror attacks on Sept. 11, 2001, and replaced a collection of private security companies that were hired by airlines. Eight of the 10 busiest days in TSA's history have come this year, as the number of travelers tops pre-pandemic levels.
The head of the agency, David Pekoske, said Wednesday that TSA has enough screeners to handle the expected crowds this weekend and through the summer.
"We have been totally tested over the course of the last couple of months in being able to meet our wait-time standards of 10 minutes for a PreCheck passenger and 30 minutes for a standard passenger, so we are ready," Pekoske said on NBC's "Today" show.
Peggy Grundstrom, a frequent traveler from Massachusetts who flew to Florida to visit her daughter and granddaughter, said the line for security in Hartford, Connecticut, was unusually long.
"It was busier than I have personally seen in the past," Grundstrom said. "But, you know, I prefer to fly unless it's very local. I'm at a stage where I don't want to travel in a car for long periods of time."
Passengers on a Delta Air Lines flight from Detroit to Amsterdam on Wednesday had to put their travel plans on hold for several hours when the plane landed in New York because spoiled meals were served in the main cabin shortly after takeoff.
Delta apologized to passengers "for the inconvenience and delay in their travels."
Nicole Lindsay thought she could beat the holiday-week travel rush by booking an early-morning flight. It didn't work out that way.
"I thought it wouldn't be that busy, but it turned out to be quite busy," the Baltimore resident said as she herded her three daughters through Palm Beach International Airport in Florida. "It was a lot of kids on the flight, so it was kind of noisy - a lot of crying babies."
Lindsay said the flight was full, but her family arrived safely to spend a few days in Port Saint Lucie, so she was not complaining.
Airlines hope the outcome is just as good for millions of other passengers scheduled to take holiday flights over the next few days.
The Associated Press contributed to this report.