Children who are under 2 years old and those who can’t wear a mask due to a disability are exempted from the order, which is is set to take effect on Monday at 11:59 p.m.
The CDC’s new rule goes further than an executive order signed by President Joe Biden last week that required face masks to be worn on federal properties and during interstate travel.
The CDC said that while it “reserves the right” to enforce the order through criminal penalties, it will be relying on an honors system practiced by passengers.
Airlines, which largely enforced self-imposed mask regulations before Biden’s order and the new CDC rule, previously called on the Federal Aviation Administration to issue a federal mask mandate, but the agency declined to, noting that it’s not a public health agency.
As of Saturday morning, the U.S. surpassed 25,000,000 cases and 436,000 deaths amid the coronavirus pandemic.