Marching and handing out fliers, students who sympathize with Palestinians under siege from Israel rallied on a handful of the nation's campuses.
Most events during Tuesday's loosely organized protests were modest and peaceful, though some demonstrators were heckled.
A pro-Palestinian rally drew about 1,000 supporters and spectators at the University of California, Berkeley, including pro-Israel demonstrators who shouted their disapproval while police kept watch.
After the rally, campus police arrested 79 protesters who stormed into a classroom building. Some students hung a Palestinian flag from a third-story window, while others marched in the hallways of the building, which houses classrooms for Middle Eastern studies.
Students for Justice in Palestine likened the current Mideast violence to the Holocaust and called for the university to divest any Israel-related investments.
As speakers made their case during the rally, counter-demonstrators tried to drown them out, crying "Stop the suicide bombings!" They also booed, cursed and chanted "Shame!"
At the same time, a small knot of people in a tent nearby read aloud the names of people killed by the Nazis, part of a 24-hour vigil for Yom Hashoah, the Jewish Holocaust remembrance day.
"They are trying to subvert language used in the Holocaust," said Eddan Katz, 26, a third-year law student and Israeli-American. "I hear no one in Israel politics today talking about the eradication of all Palestinians."
At the University of Michigan, about 50 protesters, some with arms tied and mouths gagged, paraded mutely through the Ann Arbor campus.
A group called Students Allied for Freedom and Equality said in a statement their demonstration was "to draw attention to the brutal tactics used by the state of Israel in its illegal occupation of Palestinian lands."
There were also small protests at other schools, including Ohio State University and Columbia University in New York.
At the University of Minnesota, about 75 people turned out to demonstrate. One was Hussan Mahmoud, a 28-year-old graduate engineering student from Egypt.
"I just hope this makes a difference," Mahmoud said, "but I don't see how it will.