CHICAGO - Angered by a controversial Arizona immigration law, tens of thousands of protesters - including 50,000 alone in Los Angeles - rallied in cities nationwide demanding President Barack Obama tackle immigration reform immediately.

From Los Angeles to Washington, activists, families, students and even politicians marched, practiced civil disobedience and "came out" about their citizenship status in the name of rights for immigrants, including the estimated 12 million living illegally in the United States.

"I want to thank the governor of Arizona because she's awakened a sleeping giant," said labor organizer John Delgado, who attended a rally in New York where authorities estimated 6,500 gathered.