Organizers estimated 400,000 people turned out for the march, which led to more than 100 arrests and yielded at least one skirmish between self-styled anarchists and police. More than 400 people have been arrested in protests since Thursday.

Chanting "Hey Ho, Bush Has Got to Go," the largely peaceful crowd marched past the Madison Square Garden convention site as Republicans and visitors arrived in the city for a four-day event where Bush will be nominated for another four-year term.

Police declined to estimate the size of the crowd but it stretched out more than a mile down one of the city's main thoroughfares. Thousands of police -- many clad in riot gear, some on bicycles and others on horseback -- turned out to control the crowd, who carried signs saying "Osama Loves Bush," "Bush Lies Who Dies?" and "Hate is not a Family Value."

A small group of masked anarchists set fire to a float just one block from the convention site and hurled bottles at police in riot gear who rushed them and made 11 arrests, police said.

March organizer Leslie Cagan told Reuters that despite some minor clashes, "The march has gone very, very well."

"People have come to protest the Bush administration on very many issues, but today we were united in speaking out against the Bush agenda," she said.