When Drexel University professor George Ciccariello-Maher tweeted about wanting "white genocide" for Christmas, the university's phone lines were overwhelmed.
Last month, after tweets saying "the narrative of white victimization" was behind the Las Vegas massacre, Drexel placed him on leave, citing "growing" threats and public safety.
After Princeton University professor of African-American studies Keeanga-Yamahtta Taylor called President Trump a "racist, sexist megalomaniac" in a commencement speech, threats led her to cancel public appearances.
In June, Trinity College in Connecticut shut down its campus in response to threats to a professor who shared Facebook posts that were seen as anti-white.
As such incidents have become more common, professors across the nation are asking themselves: Do I have to worry about what I say?
It's a complicated question, professors and administrators say, and one unique to a time when divisive politics and social media collide with longstanding questions about academic freedom.
"Unfortunately, the answer is yes, they should be concerned. What's that saying? Be afraid. Be very afraid," said Michael Sachs, a kinesiology professor at Temple University who heads its faculty senate. "Unfortunately, the political climate is such that anything one says in a public setting … can very easily get scrutinized."
In interviews, more than a dozen area professors said concern is growing about how incivility and outrage can affect the classroom, particularly in self-censorship.
Some said it's made them more thoughtful in lesson planning or more sensitive to students' reactions. All said they hoped that teachers ultimately would not shy away from touchy subjects.
"I see young faculty very concerned about what will happen if a student complains about them and what they're doing in the classroom," said Wendel White, an art professor at Stockton University in New Jersey. "At the same time, I also see some really great and smart and good faculty members who are grappling with really challenging materials in different disciplines … even if they don't have tenure. Because it's their belief that that's the best possible way to do their job."
Colleges have long been under pressure to fire faculty members seen as politically extreme, said Hans-Joerg Tiede, an officer at the American Association of University Professors, a nonprofit professional group often involved in issues of academic freedom.
Schools tend to come under attack during periods of societal stress, Tiede said, pointing to the Great Depression and the late 1960s and '70s.
The difference now, he said, is the reach of online outlets.
At Rutgers University, Kevin Allred said his teaching contract wasn't renewed after tweets recreating an absurdist hypothetical he had posed in class.
Allred had been discussing how political responses to gun control intersect with victims' race, when he asked whether conservatives who oppose gun control would feel the same way if he bought a gun and started shooting at white people.
Later, Allred said, he was reliving the day on Twitter when he tweeted: "Will the [Second Amendment] be as cool when I buy a gun and start shooting at random white people or no…?"
He quickly came under a barrage of criticism; Rutgers contacted police after a student complained. Officers detained Allred for evaluation, and the university placed him on leave.
A year later, Allred said, some websites remain dedicated to insulting him, and social media accounts mock him and send him death threats.
"They love to just go at you, harass you, make you afraid," he said. "They want us to be terrified."
Campuses have long been havens where lively debate is encouraged.
But Chika O. Okeke-Agulu, an art professor at Princeton, said he senses a kind of anti-intellectualism on the rise as people use social media to attack academics who grapple with controversial ideas.
A danger in the classroom is that teachers, worried about being targeted, end up censoring themselves and shy away from a topic, soften language, or approach a discussion differently.
"The hypersensitivity that particularly we in the academy have to feel about what we say, it can have chilling effects," said Shauna L. Shames, a political science professor at Rutgers-Camden.
Some young professors and graduate students, lacking tenure and still learning how to teach, worry that one misstep could derail their careers. Several said they particularly worry that those who are already targets — women, people of color, LGBT people — can be particularly vulnerable.
"As faculty, if we're going to expect our students to be global citizens and think about issues in a broader sense," said Katherine R. Goodrich, a Widener University biology professor. "We need to be good at exemplifying those behaviors and those topics without shying away from them."
Several professors said the climate of outrage was forcing them to pause more often and challenge their own assumptions, to be more thoughtful, and to make sure they connect with students.
"What I notice I'm doing much more often is really trying to stay away from personal opinions and using the sources and data, really backing up everything with facts," said J. Wesley Leckrone, who chairs Widener's political science department.
Others said they take an approach that emphasizes transparency and disclosure.
Kelly Dittmar, a political science professor at Rutgers-Camden, is already visible on social media and as a scholar at the Center for American Women and Politics at Rutgers-New Brunswick. So in class, she said, she's open about her advocacy, such as for gender equity in politics — but also makes clear that she wants students to think for themselves.
"I shouldn't be working to persuade them of my own [opinions], but instead equip them with the tools and information to refine their own belief systems," she said.
Faced with an outside climate of division and outrage, Dittmar was among the professors whose solution is to focus on the climate inside the classroom: If a professor creates an environment in which disagreeing viewpoints are welcome, and discussion can be civil but provocative, she said, then students can feel comfortable challenging each other in class and not take to social media.
Colleges and universities also are responding proactively to help professors.
Rutgers has held town hall meetings with students to discuss types of speech, said Barbara Lee, the university's senior vice president for academic affairs. The university has held training for deans and chairs to discuss academic freedom and protections under the First Amendment.
Stockton has revised its campus code of conduct to make it clearer, and is creating a task force to explore speech on campus.
Ultimately, professors said, fears of backlash can't stop professors from doing their work. And much of that work focuses on delving directly into society's most controversial pressure points.