The Oregon National Guard was activated in Portland, Ore., on Wednesday night in response to widespread violence in the city, authorities said.
At least 11 rioters were arrested. The NYPD announced about 50 arrests related to the protests. Police confiscated several weapons, including knives, and a stun gun.
Meanwhile, Trump supporters massed outside the Maricopa County Elections Department in Phoenix.
Trump has said repeatedly without evidence that mail-in votes are prone to fraud.
Both sides held rallies in Philadelphia on Thursday.
Trump activists waved flags and carried signs saying: “Vote stops on Election Day” and “Sorry, polls are closed.”