Carrboro, N.C. — Angered by a controversial Arizona immigration law, tens of thousands of protesters – including some demonstrators in Carrboro and Durham – rallied in cities nationwide demanding President Barack Obama tackle immigration reform immediately.

"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.

From Los Angeles to Washington D.C., 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 U.S.

In Durham, about 400 people lit candles at a vigil organized by El Centro Hispano, Reform Immigration for America, the Immigrant Solidarity Committee of Durham and other groups.

"Everyday I see families being ripped apart by the deportations and dreams being crushed by our broken immigration system," Julio Olmos, a community organizer at Centro Hispano in Durham, said in a statement.

Police said 50,000 rallied in Los Angeles where singer Gloria Estefan kicked off a massive downtown march. Estefan spoke in Spanish and English, proclaiming the United States is a nation of immigrants.

"We're good people," the Cuban-born singer said atop a flatbed truck. "We've given a lot to this country. This country has given a lot to us."

Public outcry, particularly among immigrant rights activists, has been building since last week when Arizona Gov. Jan Brewer signed the legislation last week. The law requires local and state law enforcement to question people about their immigration status if there's reason to suspect they're in the country illegally. It also makes it a state crime to be in the United States illegally.

The law's supporters say it's necessary because of the federal government's failure to secure the border, but critics contend it encourages racial profiling and is unconstitutional.

"It's racist," said Donna Sanchez, a 22-year-old U.S. citizen living in Chicago whose parents illegally crossed the Mexican border. "I have papers, but I want to help those who don't."

Organizers estimated about 20,000 gathered at a park on Chicago's West Side and marched, but police said about 8,000 turned out.

The event resembled something between a family festival – food vendors strolled through with pushcarts – and a political demonstration with protesters chanting "Si se puede," Spanish for "Yes we can." A group of undocumented students stood on a stage at the Chicago park and "came out" regarding their immigration status.

Juan Baca was among those students. Baca, 19, whose parents brought him from Mexico illegally when he was 4 months old, said he has had to drop out of college and work several times already because he can't qualify for financial aid.

"It's been a struggle," he said. "I missed the mark by four months."

Obama once promised to tackle immigration reform in his first 100 days, but has pushed back that timetable several times. He said this week that Congress might lack the "appetite" to take on immigration after going through a tough legislative year. However, Obama and Congress could address related issues, like boosting personnel and resources for border security, in spending bills this year.

At the White House, U.S. Rep. Luis Gutierrez, an Illinois Democrat, was among 35 people arrested in a demonstration of civil disobedience against the Arizona law.

Protests elsewhere were largely peaceful. No arrests were reported at most demonstrations; two were arrested in Los Angeles, one for vandalism and the other for drunkenness.

In Dallas, police estimated at least 20,000 attended a Saturday rally. About a dozen people there carried signs depicting the Arizona governor as a Nazi and Maricopa County Sheriff Joe Arpaio, known for his tough illegal immigration stance, as a Klansman. Organizers were asking sign holders to discard those placards.

Juan Hernandez, the Hispanic outreach coordinator for Arizona Sen. John McCain's unsuccessful presidential run, attended the Dallas rally. He said Arizona was once considered by those south of the border to be a model state with particularly close ties to Mexico.

"It went beyond what most states do," he said. "Now they are a state that goes beyond what the Constitution says you should do."

Juan Haro, 80, was born and raised in Denver, where about 3,000 people rallied. He said he thinks Arizona's new law targets Mexicans.

"This country doesn't seem to be anti-immigrant," said Haro, whose family is originally from Mexico. "It seems to be anti-Mexican."

In downtown Miami, several hundred flag-waving demonstrators – many with Cuban and Honduran flags but mostly American ones – called for reforms.

Elsewhere, an estimated 7,000 protesters rallied in Houston, about 5,000 gathered at the Georgia state Capitol in Atlanta, and at least 5,000 marched in Milwaukee. About 3,000 attended a Boston-area march.

In Ann Arbor, Mich., more than 500 people held a mock graduation ceremony for undocumented immigrant students near the site of Obama's University of Michigan commencement speech.

In Arizona, police in Tucson said an immigration rights rally there drew at least 5,000 people. Several thousand people gathered in Phoenix for a demonstration Saturday evening.

A smattering of counterprotesters showed up at rallies. In Tucson, a few dozen people showed up in support of the new law and Brewer. A barricade separated about two dozen counterprotesters from a pro-immigrant rights rally in San Francisco.

The counterprotesters there carried signs that read, "We Support Arizona" and "We Need More Ice At This Fiesta," an apparent reference to the federal Immigration and Customs Enforcement agency.

May 1 is International Workers Day, a traditional date for political demonstrations. Immigration advocates latched onto that tradition in 2006, when more than 1 million people across the country – half a million alone in Chicago – protested federal legislation that would have made being an illegal immigrant a felony. That legislation ultimately failed.