New York mayor Bill de Blasio on Thursday urged all of the city's residents to cover their faces when outside and near others to help stop the spread of the coronavirus.
"Let's be clear. This is a face covering. It could be a scarf. It could be something you create yourself at home. It could be a bandana," de Blasio told reporters.
"It doesn't need to be a professional surgical mask. In fact, we don't want you to use the kind of masks that our first responders need, that our health care workers need. Don't use those," he added.
New York is the epicenter of America's deadly COVID-19 outbreak.
The city has recorded almost 50,000 confirmed cases, including 1,562 deaths, according to the mayor's office.
As of Thursday evening, the United States had a total of more than 243,000 declared cases and over 5,900 fatalities, according to a running tally by Johns Hopkins University.
President Donald Trump told reporters at his daily White House briefing on the coronavirus that he was not considering making it mandatory for all Americans to cover their faces.
"For example on the masks, if people wanted to wear them they can. If people wanted to use scarves, which many people have them, they can.
"In many cases, scarves are better. It's thicker. Depending on the material, it's thicker," he said.
Vice President Mike Pence added that the Centers for Disease Control and Prevention (CDC) would release official guidelines on masks in the coming days.
But Deborah Birx, the coronavirus response coordinator at the White House, said it is important people do not think masks replace social distancing or hand-washing.
"We don't want people to get an artificial sense of protection," she said. "They're an additive."
California Governor Gavin Newsom made similar recommendations as de Blasio on Thursday, but stressed that masks were "not a substitute" for social distancing.
"Individuals [who] want to have face coverings... that is a good thing and a preferable thing, in addition to the physical distancing and the stay-at-home order," he said.
More than three-quarters of Americans are currently living under various forms of lockdown, including New Yorkers who have been told not to leave their residences unless absolutely necessary.