But he thought some limits were needed. “There was horrendous chalking this past semester,” said Mr. Blair, who is studying industrial design. “White supremacist, anti-Semitic, transphobic.”

“BUILD THE WALL” and “It’s ok to be white” appeared on sidewalks, students said. Then came what some students called the chalking wars, in which messages were defaced and turned into hate speech. “Smash the Patriarchy” was crossed out and rewritten as “Smash the Hooknose,” students said. “Eat the Rich” became “Eat the (((Rich))),” with the triple parentheses as a code for Jews. And “HH” — for “Heil Hitler” — appeared next to “MAGA.”

Mr. Blair said that, as a gay man who had experienced discrimination, he believed that speech and symbols could be inherently violent. “Maybe we should ban the Confederate flag,” he said.

A group called Students Against Racism formed last October to combat the chalking and other incidents they perceived as racist. Alexa Rodriguez, a sophomore who helped found the group, cited “the mental exhaustion that comes from seeing these types of messages.”

Nobody seems to know the identities of the perpetrators, who apparently acted at night, sometimes wearing masks, Ms. Rodriguez said. Left-wing students suspect the mischief was wrought by Trump supporters, and conservatives say it may have been sabotage, to make them look bad.

Ryan Hurley, president of the College Republicans, said his group was not to blame. Mr. Hurley, a sophomore majoring in business, waited outside the campus bookstore on a recent morning wearing a T-shirt that condemned sex trafficking. He showed off a photo of 800 sticks of chalk, ordered on Amazon, as if it were a cache of ballistic missiles.

He would never have written something like “HH,” he said, adding that he did not even know what it stood for until the chalking appeared. “I thought it was Hulk Hogan, honestly,” he said.