The Centers for Disease Control and Prevention (CDC) recommended "the universal use of face masks" on Friday, which includes wearing a facial covering when indoors and not at home.
"Consistent and correct use of face masks is a public health strategy critical to reducing respiratory transmission of SARS-CoV-2, particularly in light of estimates that approximately one half of new infections are transmitted by persons who have no symptoms," the agency wrote.
"Compelling evidence now supports the benefits of cloth face masks for both source control (to protect others) and, to a lesser extent, protection of the wearer," the CDC said.
The recommendation to wear masks indoors comes a day after President-elect Joe Biden said he would encourage nationwide use of masks at the start of his presidency.
On Thursday, Biden said he would urge Americans to commit to 100 days of wearing masks on his first day in office.
"The first day I'm inaugurated to say I'm going to ask the public for 100 days to mask," Biden said in an interview broadcast on CNN.