The prominence of the “Q” symbol turned parts of the audience into a tableau of delusion and paranoia — and offered stark 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…

But viewing their message boards, it’s clear that QAnon crosses a new frontier. In the black hole of conspiracy in which “Q” has plunged its followers, Trump only feigned collusion to create a pretense for the hiring of special counsel Robert S. Mueller III, who is actually working to expose the Democrats. Barack Obama, Hillary Clinton and George Soros are planning a coup — and traffic children in their spare time. J.P. Morgan, the American financier, sunk the Titanic.