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.

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.”

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.”

Hertz reported a sharp increase in one-way car rentals.

More than 1,000 flights were called off nationwide Friday — five times the number canceled Thursday, according to FlightAware, a website that tracks flight disruptions.

Reagan National Airport was hit the hardest with at least 18% of its arrivals — 81 flights — canceled Friday. The major hubs of O’Hare, Atlanta, Denver and Dallas-Fort Worth rounded out the top five airports for cancellations, but those airports only lost around 3% of their flights.

Not all the cancellations were due to the FAA order, and both United and American airlines said they were able to quickly rebook most travelers.

The airlines focused their cuts on smaller regional routes to airports where they have multiple flights a day, helping minimize the number of passengers impacted.