Thousands of people massed around Wall Street to mark the Occupy Wall Street movement's two-month anniversary, blocking streets and in some instances clashing with police, as similar protests popped up around the country.

Protesters paraded through Lower Manhattan for several hours, and about 175 people were arrested as they crowded intersections near the New York Stock Exchange, brokerage houses and banks.

Demonstrations were also planned or under way in such cities as Washington, St. Louis, Las Vegas and Portland, Ore., according to the Associated Press.

About 500 sympathizers of the Occupy protest marched downtown Los Angeles, resulting in 23 arrests, according to the AP. Protesters in Las Vegas vowed to pitch tents in front of a federal building. In Albany, N.Y., protesters from Buffalo, Rochester and other encampments were coming in by bus to join a demonstration in a downtown park. Police in Portland, Ore., closed a bridge in preparation for a march there, the AP reported.

Some Occupy Philly protesters sought a permit to Thursday to move to a new site after officials told them to vacate their camp next to City Hall to make way for long-planned plaza renovations.

In New York, two police officers were injured Thursday afternoon while responding to a call inside Zuccotti Park, the former site of Occupy Wall Street's encampment where two days earlier, police cleared out the tent city in a predawn raid. Several officers were struck in the face with a liquid, possibly vinegar, said a New York Police Department spokesman.

By midafternoon Thursday, protesters largely dispersed from the park. A group of about 300 people, flanked by police, marched north on Broadway past City Hall, led by protesters carrying a drum and a cow bell.

Occupy Wall Street organizers, with the backing of some of the city's largest unions, planned for supporters to spread out to 16 subway and train stations across the five boroughs Thursday afternoon, talking to commuters about economic inequality. They were expected to reconvene at Foley Square, just north of City Hall, to stage a march across the Brooklyn Bridge at 5 p.m. ET.

The day's events will test both the movement's resilience following its eviction Tuesday from Zuccotti Park and New York City's ability to deal with the decentralized protests.

Occupy Wall Street protesters first gathered at the park on Sept. 17. What many expected to be a short-lived demonstration instead appeared to capture growing popular resentment against corporate bailouts and economic inequity. It soon grew into a movement that spread to other cities and led to raucous protests around the world.

Earlier Thursday, protesters encountered police barricades at the entrances to Wall Street, and some sat on the ground or linked arms to block commuters trying to reach the area for the start of the work day. Police at some locations checked identification before allowing workers to cross onto Wall Street.

Some of the police hit and shoved protesters in an effort to clear the way, and one woman pinned to the ground by police was bleeding from her mouth.

The protest didn't delay the opening of the New York Stock Exchange or disrupt business, said Rich Adamonis, a spokesman for the exchange, according to the AP.

"I'm hoping they see that they are being held accountable to the 99%," said Katie Ferrari, a 23-year-old protester in New York, who said she had been linking arms with others to stop workers from passing a barricade at Hanover Street.

Ms. Ferrari, a Queens resident who works as an artist and graphic designer, said police moved aggressively to clear the sidewalk, pushing and knocking over some protesters.

Stojan Dragovich, 45, who owns a marketing business on Wall Street, stood at the same blocked intersection for more than 15 minutes, trying to get to his office. "I'm just waiting. It caught me by surprise," he said with a grim nod. "I hope I can get in. We need to work."

At the intersection of Broadway and Wall Street, protesters came to a standstill and obstructed all pathways. "Mic check, mic check," yelled one man, using the activists' method for spreading information. "We have succeeded in successfully closing Wall Street." The crowd responded with chants of "Shut it down, shut it down!"

David Fuffman, 30, a protester from Baltimore, explained the reasoning for blocking workers from entering Wall Street. "I think it's an issue of disruption of the status quo," he said. "People trying to get through make them think twice about what they do every day. You also don't have to be in the 99% to not like the way things are going."

Employees at TD Bank branch on Wall Street had locked the doors to prevent protesters from entering the building.

Thursday's protest activities began after 7 a.m., as a crowd gathered around Zuccotti Park. Organizers called on supporters to march from there to Wall Street.

In two months of protests, a heavy police presence and a warren of barricades have kept protesters from holding serious protests on Wall Street itself.

Police used motorcycles and other vehicles to block the march's progress on Nassau Street, where a mass of demonstrators chanted "We are the 99%." Elsewhere, police on horseback worked to control the crowd.

Matthew Schmidt carried a sign that reads "Greed does not equal love" as he marched.

"I have a job, I pay my bills," said Mr. Schmidt, a 38-year-old actor and a bartender. He said he understood why the police swept protesters out of Zuccotti Park on Tuesday but faulted their tactics. "I think it was done a little abruptly. A lot people were hurt who didn't need to be hurt."