On the eve of Independence Day, US airports are experiencing travel havoc due to the extreme weather warnings that are affecting more than 100 million Americans.

On Monday, more than 3,000 domestic, international, and charter flights were either canceled or delayed, according to FlightAware.

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The number of travelers through US airports on Sunday was at an all-time high, according to TSA data.

While the south and west continue to broil in a heatwave, storms are threatening a large portion of the eastern US.

According to information from the FlightAware website, United Airlines continued to be the airline that was most negatively impacted by the delays on Monday, with over 300 flights being postponed.

Over the last week, the carrier faced more delays and cancellations than any other US airline combined, totaling over 5,000.

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Saturday’s thunderstorms at United’s busiest hub in Newark, New Jersey, generated a “extended limited operating environment,” according to chief executive Scott Kirby’s memo to staff.

The week was “one of the most operationally challenging weeks I’ve experienced in my entire career,” Kirby added.

The airline announced that it will give 30,000 frequent flyer miles, which Time Magazine estimated to be worth $360 (£283), to those who were most negatively impacted by the commotion.

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The US’s extreme weather, according to Secretary of Transportation Pete Buttigieg, has “put enormous pressure on the system” and is the reason why travel has been “so chaotic” in the US.

A total of 1,500 new air traffic controllers will be hired by the Federal Aviation Administration this year, and a further 1,800 will be hired the following year, he told CBS.

Industry representatives had been worried that a new 5G rollout around airports would interfere with airplane technology before the long Fourth of July weekend.

However, a spokeswoman for the Department of Transportation informed CBS News that no significant aircraft delays were caused by the situation.