At least 300 people have gathered in a soggy Pioneer Courthouse Square as an uneasy city waits to see what a Portland protest of President Donald J. Trump will look like.

A few masked protesters have burned American flags in the square known as "Portland's Living Room."

Anti-Trump protesters burn an American flag in Pioneer Courthouse Square on Jan. 20, 2017. (William Gagan)
Anti-Trump protesters burn an American flag in Pioneer Courthouse Square on Jan. 20, 2017. (William Gagan)

Portland police have already arrested at least one protester.

Mayor Ted Wheeler has pledged to keep interstate freeways and public-transit lines open tonight, saying the Portland Police Bureau can use non-lethal force to keep traffic moving.

Meanwhile, downtown businesses like Nordstrom's and the Nike Store have boarded up their windows with plywood, hoping to avert a reprise of vandalism from anti-Trump protests in November. Nordstrom added a poignant plea to its plywood: "We [Heart] PDX."

Protesters arrive in Pioneer Courthouse Square on Jan. 20, 2017. (Joe Riedl)
Protesters arrive in Pioneer Courthouse Square on Jan. 20, 2017. (Joe Riedl)

A group of Don't Shoot Portland protesters—closely associated with the Black Lives Matter movement—arrived on the MAX from a march in Gresham. They made a dramatic entrance, chanting: "Hands up, don't shoot" as they exited the train.

That chant quickly morphed into another: "Fuck Donald Trump."

Tonight's anti-Trump march, run by the group Portland's Resistance, is scheduled to begin within the hour. The flag burning was a separate, offshoot event coordinated by a more radical splinter group of protesters.

A protester named Jeff Rosenthal watched the flag-burning approvingly.

"This is part of what it means to be American," he said. "Regardless of your opinion on the act itself, this is an essential act for the democracy that we have worked so hard for, that Americans have died for. This is what it is for."

A counter-protester named Thomas Brannon came to Pioneer Courthouse Square to toss water on the burning flags.

"I have family that died for this flag, supporting this flag," Brannon said. "Absolutely it should be illegal. That flag represents this country, that flag represents freedom, people out here are burning it. If you don't like the flag, get out of the country."

Protesters burn American flag in Pioneer Courthouse Square on Jan. 20, 2017. (Joe Riedl)
Protesters burn American flag in Pioneer Courthouse Square on Jan. 20, 2017. (Joe Riedl)
Portland anti-Trump protesters on Jan. 20, 2017. (Joe Riedl)
Portland anti-Trump protesters on Jan. 20, 2017. (Joe Riedl)
Portland anti-Trump protesters on Jan. 20, 2017. (Joe Riedl)
Portland anti-Trump protesters on Jan. 20, 2017. (Joe Riedl)
Portland protest organizer Gregory McKelvey negotiates with police officers for use of a megaphone on Jan. 20, 2017. (Joe Riedl)
Portland protest organizer Gregory McKelvey negotiates with police officers for use of a megaphone on Jan. 20, 2017. (Joe Riedl)