"What happened in Arizona proves that racism and anti-immigrant hysteria across the country still exists. We need to continue to fight," said Lee Siu Hin, a coordinator with the Washington, DC-based National Immigrant Solidarity Network.

Activists believe opposition to Arizona's new law could be the catalyst needed to draw record-breaking crowds.

That's when more than a million across the country united to fight federal legislation considered anti-immigrant. Though the bill, which would have made being an illegal immigrant a felony, was unsuccessful, it triggered massive marches across the nation.

Since then, the May 1 movement has fractured and attendance has dropped sharply as attempts to reform federal immigration policy fizzled. In 2006, nearly half a million people took to Chicago's streets. Last year, fewer than 15,000 participated.

But after the Arizona law was signed into law last week, immigration reform advocates have seen a flurry of activity.

Relying on online social networking, churches and ethnic media to mobilize, activists have called for a boycott of Arizona businesses and protested outside Arizona Diamondbacks baseball games.