As I recently wrote in The Atlantic, during the 1918-19 pandemic flu, the Surgeon General of the U.S. could do little more than urge state and local governments to close schools and prohibit large gatherings. But then-U.S. Surgeon General Rupert Blue also urged Americans to make face masks and wear them in public. Newspapers printed instructions, and the American Red Cross produced thousands of masks. These were not available for purchase. Here we are, more than a century later, with the Surgeon General explaining to the American public how to make a face covering, and urging that it be worn.