Here is an overview of how the government's recommendations changed over time. They were explicitly advising against wearing face masks and saying they don't work. Ex:

U.S. Surgeon General Dr. Jerome Adams tweets that wearing a face mask will not prevent the public from contracting the novel coronavirus.

“Seriously people — STOP BUYING MASKS!” he wrote in a tweet that was later deleted. “They are NOT effective in preventing general public from catching #Coronavirus