Air travel in the United States could soon "slow to a trickle," authorities warned Sunday as thousands more flights were cancelled or delayed and passengers faced chaos triggered by the federal government shutdown.

Transportation Secretary Sean Duffy said the number of flights being snarled or cut would multiply if the funding impasse between Democrats and Republicans continues while Americans gear up to travel for the Thanksgiving holiday later this month.

"It's only going to get worse," Duffy said on CNN's "State of the Union," a Sunday news talk show. "The two weeks before Thanksgiving, you're going to see air travel be reduced to a trickle."

On Sunday afternoon, more than 1,800 flights within the United States and to and from the US had been cancelled and there were close to 5,700 d

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