Travelers head down an escalator after clearing through a security checkpoint at Denver International Airport on Friday. (AP Photo/David Zalubowski)

Anxious travelers across the U.S. felt a bit of relief Friday as airlines mostly stayed on schedule while still cutting more than 1,000 flights largely because of the government shutdown.

Plenty of nervousness remained, though, as more canceled flights are coming over the next week to comply with the Federal Aviation Administration’s order to reduce service at the nation’s busiest airports.

The order is in response to air traffic controllers — who haven’t been paid in nearly a month as the shutdown drags on — calling out of work in higher numbers as they deal with financial pressure.

While it’s left some passengers making backup plans and reserving rental cars, the flights canceled Friday represented just a small portion of overall flights nationwide.

Passengers still faced last-minute cancellations and long security lines at the 40 airports targeted by the slowdown including major hubs in Atlanta, Dallas, Denver and Charlotte, North Carolina.

Airlines expect limited disruptions this weekend and stressed that international flights are not expected to be affected.

But if the shutdown persists much longer, and more controllers call out of work after they miss their second paycheck on Tuesday, the number of cancellations could jump from the initial 10% reduction of flights to 15% or 20%, Transportation Secretary Sean Duffy said on Fox News on Friday.

Long lines and, for some, long drives

Those who showed up before sunrise Friday at Houston’s George Bush Intercontinental Airport faced security lines that barely moved, prompting some people to lie down while they waited.

“It was snaking around all different parts of the regular area,” Cara Bergeron said after flying from Houston to Atlanta. “I’ve never seen anything like that.”

Others were less fortunate.

Karen Soika from Greenwich, Connecticut, found her flight out of Newark, New Jersey, was rebooked for an hour earlier. Then she learned her plane was actually leaving from New York’s John F. Kennedy International Airport, at least an hour away.

Soika, a surgeon, unsuccessfully tried to book a rental car to get to Utah for a weekend trip before settling on an option that seemed straight out of Hollywood.

“I’m going to U-Haul and I’m going to drive a truck cross-country,” said Soika, who is advising on medical scenes there for a spinoff of the TV series “Yellowstone.”