On Monday, Americans woke up to the worst mass shooting in modern history.

The night before, a white man—whom police have since identified as 64-year-old Stephen Paddock—opened gunfire from his room high up in the Mandalay Bay Resort in Las Vegas onto a crowd of concert-goers below. He killed 58 people, and injured hundreds of others. “It was an act of pure evil,” said President Donald Trump in a brief statement Monday.

The police later found the gunman dead, apparently in a suicide, in his hotel …