Nearly two years of planning could not prevent 1.5-hour long wait times in security lines at Hartsfield-Jackson International Airport on the day after the Super Bowl in Atlanta.

With unprecedented crowds at the world's busiest airport, security lines Monday stretched through the domestic terminal atrium, down hallways, around baggage claim carousels and extended alongside Delta ticket counters.

Airport officials estimated nearly 100,000 passengers passed through security checkpoints. Typically, 60,000 to 65,000 travelers are screened on a regular Monday, airport general manager John Selden said.

As the crowds began to grow Monday, Selden said, "This is our game day for Hartsfield-Jackson. This is the last impression all travelers will have."

By 8:20 a.m., a Delta official was telling those at the end of the queue that they could take a shuttle to the international terminal on the other side of the airport for shorter lines. The long lines in the domestic terminal persisted through the morning and into the afternoon, reaching more than 1.5 hours long during the worst periods.

Even seasoned business travelers accustomed to peak period congestion were shocked to see the lines.

“I’ve never seen it like this — ever,” said business traveler Gudni Vilmundarson. “I’m just shocked and surprised.”

In a PreCheck line, David Arpin, a traveler from Rhode Island, was told it would be a 30-minute wait.

“It’s a cluster,” Arpin said, adding that it’s a good thing he had arrived three hours early.

Patience wore thin for some.

“This is outrageous. It’s almost like they didn’t plan for it,” said Lisa Gartland, a traveler returning to the Bahamas after attending the Super Bowl. “It’s ridiculous.”

Airport officials had developed plans to manage passenger flows throughout the terminal, even removing chairs in the atrium to allow more room for lines.

“We’ve established a plan to essentially use every available square foot and fill it with queuing,” said Hartsfield-Jackson assistant general manager of planning Tom Nissalke. Although passengers were in some of the longest lines ever seen at the Atlanta airport, the lines often moved quickly for much of the day.

But the Atlanta airport is still limited by a single domestic terminal handling the vast majority of passengers. Its design usually allows for the efficient operations and quick connections the Atlanta airport is known for.

But the drawback is the single domestic terminal as the entry to gates. The infrastructure allows only so many passengers at a time to be processed — even with hundreds of employees and volunteers were on hand.

“It’s a funnel,” said TSA spokesman Mark Howell.

Airport and airline officials had pushed out a message that travelers should check out of their hotel five hours before their departure time Monday and head to the airport after the game. They had hoped to process passengers through security overnight to spread out the flood of Super Bowl fans. Delta had hospitality counters to hand out blankets, pillows and amenity kits to passengers staying overnight.

But not many joined in on the airport sleepover.

John Bergquist, a Boston police officer, did. Around 4 a.m., he said he hadn’t seen any crowds at the airport.

“I expected to see more people,” said Bergquist, a Patriots fan. “I think if we had lost, there’d be a lot of people getting out of town faster. But that’s not the case.”

Selden also said Sunday evening’s good weather may have prompted Patriots revelers to stay out longer celebrating, with bars open until 4 a.m.

Employees stood ready at counters to handle overnight customers, but were left facing mostly empty concourses.

Instead, travelers did not begin arriving en masse until close to 5 a.m.

The crowds reached a peak shortly after 8 a.m. The chaotic atmosphere left some passengers confused about where to go to get to the end of the correct line. Airport workers directed travelers like traffic cops, but lines rapidly extended and doubled back or shifted, making it difficult to sort the throngs of people.

Luke Lavash, headed back to Boston was patient because he was warned the wait could be three hours — and because his Patriots won.

“It’s a lot of fun, but it’s a long wait. If we had lost, it wouldn’t be as much fun.”

Airport employees seemed taken aback by the crowds, as well.

“Oh my God!” one said to two coworkers. “I’ve never seen anything like this.”

Some passengers missed flights.Others were anxious, as they waited, about whether they’d make theirs.

“I knew it was going to be more crowded than usual, which is why I gave myself a two-hour buffer. But it looks like that’s going to be used up in the line,” said traveler Brittany Donley, leaving from Atlanta on a business trip. “Hopefully, I’ll make it.”

One major choke-point was PreCheck lines. About 40,000 of Monday’s 100,000 passengers at checkpoints were enrolled in the program, Howell said.

Many travelers took the wait in stride.

“It’s Monday after the Super Bowl,” said Alexis Armand, who was returning to Orlando. “So we expected this would be this crazy.”