Delta Air Lines said in a statement that masks - or appropriate face coverings - will be required for all employees and customers starting at the check-in lobby and across Delta touch-points including Delta Sky Clubs, boarding gate areas, jet bridges and onboard the aircraft for the duration of the flight. The airline noted the move was in line with best practice guidelines from the Centres for Disease Control and Prevention (CDC) and becomes effective on 4 May.
Frontier Airlines said in a statement that beginning 8 May, all customers will be required to wear a face-covering over their nose and mouth throughout their journey through ticket counters, gate areas, and onboard our aircraft.
"This effort is yet another activity we are taking to help you feel more comfortable when flying with Frontier", the statement said, adding that airport employees and flight crews are already required to wear face coverings.
American Airlines said aside from requiring the use of face masks, the airline will also provide sanitizing wipes for customers on select flights.
"Your well-being is at the forefront of every decision we make, and we're committed to keeping you updated as we move forward", American Airlines Senior Vice-President of Customer Experience Kurt Stache said in a statement.
Based on CDC guidance, a suitable face covering should be an item of cloth that should fit snugly against the side of the face and that should be secured with ties or ear loops. It should also include multiple layers of fabric and allow for unrestricted breathing.
The CDC recommends surgical masks and N-95 respirators be reserved for healthcare workers and other medical first responders. Its policy does not apply to very young children who are unable to maintain a face covering.
As of Friday, the number of confirmed COVID-19 cases in the US has climbed to 1,062,446, with 62,406 fatalities, according to the CDC's latest estimates.