On January 20, the day of his inauguration as the 46th President of the United States, Joe Biden signed an executive order mandating masks on federal property, which extends to national parks.

The executive order requires federal employees and visitors to wear masks and maintain physical distance while on federal lands, including national parks and federal monuments.

According to the executive order, “It is the policy of my Administration to halt the spread of coronavirus disease 2019 (COVID-19) by relying on the best available data and science-based public health measures. Such measures include wearing masks when around others, physical distancing, and other related precautions recommended by the Centers for Disease Control and Prevention (CDC). Put simply, masks and other public health measures reduce the spread of the disease, particularly when communities make widespread use of such measures, and thus save lives.”

According to Reuters, Biden also plans to require anyone in airports or on public transportation, including airplanes, intercity buses, and trains to wear masks. Many airlines and train companies (including Amtrak) have already mandated mask-wearing, though it hasn’t been required by federal law.

The mask mandate has long been a tenet of Biden’s campaign. Back in October, he said, “As president I will mandate mask-wearing in all federal buildings and all interstate transportation because masks save lives — period. Wearing masks is not a political statement; it is a scientific imperative.”