Heading to the airport? Make sure to wear comfortable shoes.

As travel comes roaring back, people are walking longer distances from the curb to the gate — past Hudson News, Chanel and Estée Lauder duty free, lounges, Auntie Anne's, and Starbucks. And that's just the first leg. These days, your concourse walk never seems to end.

"I have just travelled thru the new LaGuardia airport. It confirms a theory of mine," former Treasury Secretary Larry Summers recently observed. "The newer the terminal, the less convenient it is to use because all the walks are longer. I wonder why?"

Treks at the airport have been getting worse ever since security changes were implemented after the September 11, 2001, attacks. More changes came during the pandemic. Larger aircraft — which mean planes tend to be spaced out farther for takeoff and landing safety — have made hikes at the airport even longer.

But it's mostly because bigger is better for the airport business, even if it's harder on your feet. In Newark, Chicago and other cities' airport terminals, moving walkways have been removed to make room for more shops and restaurants.

"You get to the gate and you're exhausted," said Henry Harteveldt, who covers the travel industry for Atmosphere Research Group. "You are dealing increasingly with airports that are designed around financial objectives and safety. The traveler gets lost in the dust."

Designing 21st-century travel

Many US airports were built during the middle of the 20th century, and have undertaken massive expansion plans in the 21st. New gate extensions and recent renovations have made concourses longer.

After September 11, security checkpoints were added to existing terminals and essentially divided terminals in two, increasing the space travelers need to walk, said Alexander Thome, who leads design firm Stantec's US airport work.

Airports have added more retail and concession stands in terminals as airlines pull back on in-flight meals. This has pushed airports to offer more amenities in their terminals that aren't offered on-board, he said.

Airports bring in revenue in two main ways: Aeronautical revenue, such as fees airports charge to airlines to use runways, taxiways and parking. And non-aeronautical revenue — parking and rental car fees, retail rents, and advertising.

Airports are trying to increase the portion of non-aeronautical revenue they draw. Operators have added more stores, restaurants and bars, especially as more travelers take mass transit and rideshares to airports and parking income declines.

"People joke that today airports are shopping malls that have airplanes parked outside," Harteveldt said. "If you look at design of terminals, much of the added space is given over to retail services."

Planes have also gotten bigger to cram more passengers on board — known as "upgauging" — and airlines have retired some of their smaller planes. United, for example, is replacing 200 smaller regional jets that carry about 50 passengers each.

Larger planes mean they need to be spaced farther apart on the tarmac.

"There's a much better business case for larger planes. That's pushing airlines to upguage their fleet," said Wilson Rayfield, executive vice president of aviation at Gresham Smith, an architectural firm. "When you park 10 planes next to each other and they're 75 feet, it naturally translates to a much longer walk."

'Fitness trail'

Sprawling airports also create hassles for crews and airport employees trying to make flights take off on time.

Some airports have added electronic signs that estimate for travelers how many minutes it will take them to get to their gate or how long it will take terminal-linking monorails to arrive.

One of the longest airport treks in the United States is at Dallas Fort Worth, where the walk from an entrance in Terminal B to Terminal E is 2.16 miles, according to a study by shoe company Kuru Footwear. (Luckily, the airport has a train.)

Phoenix's Sky Harbor International Airport has a "fitness trail" where travelers can view mountains, parks and other city landmarks from the concourses.

Some new airport terminals have recently opened without moving walkways. Travelers were not happy.

Last year, Orlando International Airport opened a new $2.8 billion terminal, but it left out moving walkways. Airport leaders are now voting on a plan to install them, after multiple complaints from travelers.

Salt Lake City International Airport in 2020 opened a new terminal, but it has been a major source of criticism for its walks to the gate, which can take more than 20 minutes. The airport is now building a tunnel to shorten the walk from security to the concourse.

So, are people missing flights now because they have to walk so far? Well, that's the good news, sort of. Weather-related flight delays have been so common over the past year that millions of people are still being left waiting at the gate.