Thousands protest Arizona's controversial immigration bill in Phoenix (AP)
Thousands of people from all over the US have marched on the Arizona state capital to protest at the state's tough new crackdown on illegal immigration.
Marchers carrying signs, banners and flags from the United States and Mexico filled a five-mile stretch of central Phoenix on Saturday. Dozens of police officers lined the route and helicopters hovered overhead.
Police would not estimate the size of the crowd, but it appeared at least 10,000 to 20,000, braved temperatures forecast to reach 95 degrees Fahrenheit by mid-afternoon. Organisers had said they expected the demonstration to bring as many as 50,000 people.
The new law requires police conducting traffic stops or questioning people about possible offences to ask them about their immigration status if there is "reasonable suspicion" that they are in the country illegally.
Critics of the law, set to take effect on July 29, say it unfairly targets Hispanics and could lead to racial profiling, but supporters say Arizona is trying to enforce immigration laws because the federal government has failed to do so.
About 300 people also rallied at the Texas Capitol in Austin, and another 300 people protested at the US Embassy in Mexico City demanding legalisation for undocumented Mexican workers in the US.
Some marchers chanted "si se puede," a phrase coined by Hispanic civil rights leader Cesar Chavez that roughly means "yes we can". Others took aim at President Barack Obama, demanding that he prioritise comprehensive immigration reform that would create a pathway to citizenship for illegal immigrants now in the country.
Some opponents of the law have encouraged people to cancel conventions in the state and avoid doing business with Arizona-based companies, hoping the economic pressure forces a repeal.
But supporters of Arizona's law organised a rally of their own at a baseball stadium in suburban Tempe, encouraging like-minded Americans to "buycott" Arizona by planning holidays in the state.
"Arizona, we feel, is America's Alamo in the fight against illegal and dangerous entry into the United States," said Gina Loudon of St Louis, organising the "buycott". "Our border guards and all of Arizona law enforcement are the undermanned, under-gunned, taxed-to-the-limit frontline defenders trying to hold back the invasion."