Flight delays and cancellations are piling up Sunday across the U.S. after the Federal Aviation Administration cut flights at 40 U.S. airports on Friday following a monthlong government shutdown.

Despite hopes the federal government shutdown could end this week, air travelers in the United States are still in for a rough few days of cancellations and delays nationwide before taking to the skies gets back to normal.

U.S. airlines canceled more than 2,700 flights on Sunday as Transportation Secretary Sean Duffy warned that air traffic across the nation would “slow to a trickle” if the federal government shutdown lingered into the busy Thanksgiving travel holiday season.

Airlines for America said that when the Federal Aviation Administration flight-reduction order reaches 10% on Nov. 14, the group estimates a daily average U.S. economic impact of between $285 million and $580 million.

There were widespread cancelations and delays at airports around the United States on Monday as the ongoing government shutdown reached day 41. The stoppage, which is the longest in American history,

Southwest Airlines said it was cutting more than 400 flights scheduled for early this week due to ongoing air traffic restrictions issued during the federal government shutdown.