Texas Governor Greg Abbott has issued an executive order that all Texans don face coverings in public in counties with 20 or more Covid-19 cases.
Texas has seen a surge of hospital admissions in recent days, hitting a record high of more than 8,000 virus cases in a single day on Wednesday.
"Wearing a face covering will help us to keep Texas open for business," Mr Abbott said, announcing the order.
After an initial warning, those who refuse will face a fine up to $250.