The Federal Aviation Administration early Monday lifted its restrictions on commercial flights that were imposed at 40 major airports — including Chicago's O'Hare and Midway international airports — during the longest government shutdown in U.S. history.

Airlines were given the green light to resume their regular flight schedules at 5 a.m. CST. But travelers were advised still to be ready for possible disruptions.

Citing safety concerns as staffing shortages grew at air traffic control facilities during the shutdown, the FAA issued an unprecedented order to limit traffic in the skies. It had been in place since Friday, Nov. 7, affecting thousands of flights across the country.

The flight cuts started at 4% and later grew to 6% before the FAA on Friday rolled the restrictions back to 3%, citing continued improvements in air traffic controller staffing since the record 43-day shutdown ended on Wednesday, Nov. 12.

One day during the travel disruption, nearly 3,000 flights were cut.

The return to normal flight schedules is a big relief for travelers around the country, and in particular for anyone who might be flying out of O'Hare this week or for Thanksgiving.

AAA expects 6 million Americans to fly for the Thanksgiving holiday despite recent concerns about delays and cancellations.

"I think the things we should be looking out for are weather-related incidents that could kind of throw the system out of whack, or outages," said Brian Kelly, Founder of The Points Guy, "but overall, I, I think things are looking good."

Despite the end of the FAA's flight restrictions, travelers at O'Hare on Monday were still worried while headed to the airport.

"I was a bit concerned. I'm a busy businessperson, so I did not have a lot of time to look into these things and thought this morning, 'Is everything going to be ok?'" Katie Fish said as she was flying to Honolulu. "Thank goodness this happened before the holidays, because we all deserve good getaways and a smooth transition from here to family and back again."

Experts still recommend checking airline apps for any weather or operational delays, especially on busy travel days.