The prominence of the “Q” symbol turned parts of the audience into a tableau of delusion and paranoia — and offered evidence that QAnon, an outgrowth of the #Pizzagate conspiracy theory that led a gunman to open fire in a D.C. restaurant last year, has leaped from Internet message boards to the president’s “Make America Great Again” tour through America.

“Pray Trump mentions Q!” one user wrote on 8chan. He didn’t need to. As hazy corners of the Internet buzzed about the president’s speech, his appearance became a real-life show of force for the community that has mostly operated behind the veil of anonymity on subreddits.