About 400 anti-Wall Street protesters were arrested on Saturday after they swarmed the Brooklyn Bridge and shut down a lane of traffic for several hours.
New York police say some demonstrators spilled onto the roadway on Saturday night after being told to stay on the pedestrian pathway. They face disorderly conduct and other charges. The lane has since reopened.
Occupy Wall Street demonstrators are railing against corporate greed, global warming and social inequality, among other grievances.
The group has been camped near the US financial district for two weeks and clashed with police on earlier occasions.
The protesters forced the temporary closure of bridge when they marched into traffic, prompting dozens of arrests, New York police and demonstrators said.
The activists first occupied a small park in lower Manhattan two weeks ago to protest corporate bailouts and corporate influence in politics.
A New York Police Department spokesman told AFP, "there were also several hundred protesters who decided to walk on the roadway and who blocked traffic. Some heeded the warnings, some left, and arrests were made.''
The group inspired by the pro-democracy Arab Spring movements said on its website that "at least 50'' protesters had been arrested, though the NYPD would not confirm the figure.
Police shut down the Brooklyn Bridge at between (0700-0800 AEDT), the NYPD spokesman said, adding that he could not confirm how long the bridge was closed.
"There were several hundred (more) protesters who walked on the pedestrian walkway of the Brooklyn Bridge and there were no incidents,'' he told AFP.
Occupy Wall Street said it had staked its ground in downtown Manhattan "as a symbolic gesture of our discontent with the current economic and political climate.''
"We are all races, sexes and creeds. We are the majority. We are the 99 per cent. And we will no longer be silent,'' it added.
Protesters have added police brutality to their lengthy and still vaguely defined list of grievances after a senior officer used pepper spray against four demonstrators who had already been shut inside a police pen a week ago.
In Boston on Saturday, twenty-four protesters were arrested and charged with trespassing as a vast crowd marched outside Bank of America offices.
Right to the City, the coalition of advocacy groups that organised the demonstration, said the event was held to protest corporate greed and to stop bank foreclosures.
According to organisers, some 3,000 people marched outside the bank. Police did not provide a crowd estimate.