Those passengers can expect to see heavier-than-usual security in the aftermath of recent deadly attacks on airports in Belgium and Turkey.
The extra measures may help a bit. But security experts say making airports safer is a huge challenge because public areas are designed for commerce, not security.
Think about it. Security lines are set up to keep passengers from boarding planes with guns, bombs or other weapons. That makes flying safer.
But at major airports, thousands of people may be standing in ticket lines, checking luggage, eating at restaurants and shopping for T-shirts — all before they ever approach the screening area.
In fact, the very existence of Transportation Security Administration checkpoints could make public portions of the airport more attractive to terrorists, according to Douglas Laird, who heads Laird & Associates, an aviation security consulting firm. "The long security lines create a target-rich area" as people cluster together with nowhere to duck, Laird noted.
"Terrorists go after soft targets. If they can't get to the airplane, then they attack the airport," he said.
In Istanbul on Tuesday, terrorists arrived in a taxi and began shooting near the airport entrance.
Istanbul has long had much tighter security systems than most airports. Travelers there go through double screenings.
Still, a deadly attack could happen because the taxi was able to pull up to the airport's "arrivals" area. As is typical at airports, security is tighter in the "departures" area where people are heading to flights, not arriving from them. So the terrorists in Turkey could quickly kill 42 people outside the airport's secured areas.
Back in March, terrorists took a taxi to the Brussels airport, entered the open doors and — before ever reaching a security checkpoint — exploded bombs hidden in suitcases.
In the U.S., there have been smaller attacks in public areas. On July 4, 2002, a lone gunman shot and killed two people at the ticket counter of El Al, Israel's national airline, at Los Angeles International Airport. In 2013, another lone gunman opened fire at the same airport, killing a TSA officer.
Trying to redesign this country's hundreds of airports to boost security would be a financial and political challenge. Passengers already are annoyed by TSA lines inside airports; moving those long lines to areas away from the terminal would add greatly to travel times — and complaints. And vehicle checkpoints away from the terminal would likewise add huge hassles for travelers.
Even if Congress were to appropriate billions of dollars for drastic design changes and additional TSA guards to expand secured areas, local airport authorities may not want to surrender more turf to federal agents.
That's because operators of restaurants and shops in public areas of airports can generate much more revenue by doing business in open environments. They know that while travelers passing through, say, Israel, expect extremely high levels of security, Americans are accustomed to hanging out at airports, spending money.
For example, inside Atlanta's Hartsfield-Jackson airport, the Atlanta Chophouse & Brewery is a popular steakhouse that invites locals to come by for "cocktail receptions, business dinners and celebrations." One of the selling points is that it is "located pre-security in the Atlanta Airport Atrium."
Reducing such open access could wreck a flourishing business model and discourage use of airports and air travel.
Reese McCraine, a Hartsfield-Jackson spokesman, said that rather than redesign the airport, security officials "are maintaining a hypervigilance and have increased the visible presence of law enforcement," even though there is no "imminent threat."
At the LA airport, officials released a statement saying they are using random checkpoints at airport entrances and are being "vigilant."
Such efforts can help, Laird said, but "there's nothing you can do to be completely safe. You plug one hole and the water comes out someplace else."