U.S. airlines again canceled more than 1,000 flights Saturday mostly because of the government shutdown and the Federal Aviation Administration's order to reduce air traffic.

The slowdown at 40 of the nation's busiest airports is now in its second day and so far hasn't caused any widespread disruptions. More than 1,000 flights were canceled Friday, according to FlightAware, a website that tracks air travel disruptions.

"We all travel. We all have somewhere to be," said Emmy Holguin, 36, who was flying out of Miami on Saturday to visit family in the Dominican Republic for the week. "I'm hoping that the government can take care of this."

Analysts warn that the upheaval will intensify and be felt far beyond air travel if the cancellations pick up and move closer to the Thanksgiving holiday.

Already there are concerns about the impact on cities and businesses that rely on tourism and the possibility of shipping interruptions that could delay getting holiday items on store shelves.

Here's what to know about the flight reductions:

The first day of the Federal Aviation Administration's slowdown saw more than 1,000 flights canceled, according to FlightAware, a website that tracks flight disruptions.

More than 950 were off for Saturday — typically a slow travel day. The airport serving Charlotte, North Carolina, was by far the hardest hit with 120 arriving and departing flights canceled by midday.

Airports in Atlanta, Chicago, Dallas, Denver and Orlando, Florida, were among the most disrupted. Staffing shortages in Charlotte and Newark, New Jersey, were slowing traffic too.

Not all the cancellations were due to the FAA order, and those numbers represent just a small portion of the overall flights nationwide, but they are certain to rise in the coming days if the slowdown continues.

The FAA said the reductions impacting all commercial airlines are starting at 4% of flights at 40 targeted airports and will be bumped up again Tuesday before hitting 10% of flights on Friday.

Transportation Secretary Sean Duffy warned this week that even more flight cuts might be needed if the government shutdown continues and more air traffic controllers are off the job.

Air traffic controllers have gone without paychecks for nearly a month as the shutdown continues, leading many to call in sick and add to already existing staffing shortages.

Most controllers are working mandatory overtime six days a week during the shutdown without pay, and some are taking second jobs to pay their bills, the National Air Traffic Controllers Association has said.

Most were relieved to find that airlines largely stayed on schedule Friday, and those whose flights were called off were able to quickly rebook. So far, longer international flights haven't been interrupted.

There's still a lot of uncertainty about what flights will be canceled next.

And not everyone has the means to pay for a hotel or deal with a last-minute disruption, said Heather Xu, 46, who was in Miami on Saturday after a cruise and flying home to Puerto Rico.

"Travel is stressful enough, then you put these disruptions in place and it really makes everything more challenging," she said.

Rental car companies reported a sharp increase in one-way reservations Friday, and some people are simply canceling flights altogether.

First, there's the potential for higher prices in stores, as nearly half of all U.S. air freight is shipped in the bellies of passenger aircraft.

Major flight disruptions could bring higher shipping costs that get passed on to consumers, said Patrick Penfield, professor of supply chain practice at Syracuse University.

More losses will ripple through the economy if the slowdown continues — from tourism to manufacturing, said Greg Raiff, CEO of Elevate Aviation Group.

"This shutdown is going to impact everything from cargo aircraft to people getting to business meetings to tourists being able to travel," he said. "It's going to hit the hotel taxes and city taxes. There's a cascading effect that results from this thing.''