The Angel Food Bakery & Donut Bar baked nearly 400 doughnuts and crullers between 10 p.m. and 4 a.m. in anticipation of the crush of holiday travelers Friday morning at Minneapolis-St. Paul International Airport.

On the tarmac outside, baggage handlers swarmed near the bellies of late-arriving jets to unload luggage as passengers peered out through porthole-like windows. As morning approached, slumbering passengers with early-morning connections stirred in Terminal 1 for what travel experts said would be a second day of record crowds.

The industry group Airlines For America predicted some 51 million people across the country would take to the skies between Dec. 15 and Jan. 4, up 3.5 percent over last year. The group said Dec. 21, 22 and 26 would likely be the busiest.

Some 35,600 passengers were expected to be screened Friday, making it the busiest day for passengers clearing security, according to the Metropolitan Airports Commission (MAC), which operates MSP Airport. Thursday was the second-busiest day of the season, with 33,500 travelers expected to be screened, although these figures don’t include passengers making connections at MSP.

But before the morning onslaught, an eerie calm settled throughout this 24/7 makeshift city. The night owls of the overnight shift toiled in the wee hours of Friday morning, and the passengers who found themselves waiting for a connection took solace in MSP’s empty corridors. Shops and restaurants were shut tight.

The peace was interrupted only by the occasional whir of a vacuum cleaner and soft jazz that drifted across the sound system.

“I like working nights. It’s quiet here,” said Ken Pervenanze, a baker at the Angel Food Bakery on the E Concourse. “I can work without distraction.” The bakery was a rare hive of activity, with oldies music blasting, as Pervenanze iced and sugared the doughnuts.

Elsewhere, travelers snoozed awkwardly at boarding gates or wandered about looking for a snack or a cup of coffee. The newly renovated McDonald’s in Terminal 1 appeared to be the only food outlet open.

Richard Bridges, an inspirational speaker and author, sat at the McDonald’s about 1:30 a.m. waiting for an early-morning flight to his home in Las Vegas. “I travel a lot,” he said. “I knew I’d have a few hours to kill.”

Bridges was well-equipped to pass the time, watching YouTube videos of the comedian John Paragon on his laptop while listening to Tony Bennett. “You gotta have Tony Bennett,” he advised.

Cameron Kvittem meandered about an empty mall in Terminal 1. “I’m looking for a nice, comfortable chair,” said the Rochester native who was returning home for the holidays. After arriving from Denver on a Frontier Airlines flight that was more than an hour late, he had a little over three hours to rest before catching a shuttle to Rochester.

Some travelers found themselves at MSP because of last-minute scheduling changes.

Seattle resident Edward Balika, who owns a trucking firm, was hoping to get home in time for a family celebration — by long-haul truck. But that didn’t work out as planned, so he located the nearest airport — MSP — and booked a flight west.

He spread out across several seats at a gate on the E Concourse early Friday, fluffed up a pillow and settled in.

The night could have been highly stressful had an expected snowstorm arrived in the Twin Cities. But the snow instead passed through a southern stretch of the state.

Either way, José Beltrán, the MAC’s assistant manager of airside operations, was ready. Beltrán is part of an army of some 19,000 employees who work at the airport.

Working the night shift into Friday morning in an office above the E Concourse, Beltrán’s job involves maintaining the safety of MSP’s runways and taxiways.

Had there been snow that evening, he would have coordinated its quick removal, with the help of MAC’s field maintenance crew, Air Traffic Control and the airlines. “We’re kind of like the eyes of the airport,” he said.

Shortly after midnight, Beltrán donned a blue jacket with a big “Airside” logo across the shoulders and hopped into a pickup truck to inspect the runways and taxiways he oversees. The 3,400-acre expanse, punctuated with blue, white and gold lights, is especially surreal at night.

Beltrán maneuvered the truck to Runway 17-35 to check on two MAC electricians changing an approach light. As the wind howled, they made the switch in short order, readying the runway for another busy day.