Organisers predict a big coast-to-coast turnout in protests planned for Saturday that will stretch from New York on the eastern seaboard to San Francisco on the west coast, and even hope to picket close to President George Bush's private Texas ranch in Crawford.
"Events from Anchorage, Alaska to St Petersburg, Florida, (and) Crawford, Texas," said Dustin Langley, a spokesman for the anti-war coalition ANSWER (Act Now to Stop War and End Racism).
Bush is expected to be attending an election campaign stop in Florida during the demonstrations.
The biggest demos are touted to occur on the streets of New York, Chicago, Los Angeles and San Francisco, a stronghold of US counter-culture.
Organisers hope the overall turnout will match the large crowds that took to the streets preceding the invasion.
They expect "tens of thousands" to march in New York alone carrying banners reading "End Colonial Occupation," and "Bring The Troops Home Now."
Protesters from Vermont and North Carolina are expected to travel to New York to support the Manhattan demonstrations.
"Now people in the United States, like in Spain, are fed up with the occupation of Iraq and with US arrogance and will show it"
ANSWER, San Francisco
The second-biggest turnout is foreseen in San Francisco, one of the country's most politicised city's, according to ANSWER's San Francisco-based Bill Hackwell.
More modest crowds are expected in Los Angeles, but their ranks are likely to be lit by some celebrity wattage with Hollywood stars Martin Sheen and Tim Robbins likely in attendance.
The shock election in Spain of Socialist prime-minister-elect Jose Luis Rodriguez Zapatero who has signalled he will withdraw Spanish troops from Iraq, is likely to spur support for Saturday's demos, organisers say.
Spain's outgoing prime minister, Jose Maria "Aznar hooked himself to Bush's cart of war and lost. Now people in the United States, like in Spain, are fed up with the occupation of Iraq and with US arrogance and will show it," Hackwell said.
"Bush's poll numbers are dropping," said an optimistic Langley, hoping this will also be reflected on the streets on Saturday.
One of the biggest anti-invasion demos occurred on 15 February in New York when 250,000 people took to the streets.
Some 200 protesters, including families of soldiers killed in Iraq, had gathered on Monday in front of the White House in Washington calling for an end to the US occupation of Iraq.