The demonstrations were sparked by a grand jury’s decision not to bring criminal charges against Darren Wilson for killing Michael Brown. Once again it has highlighted the plight of young black men shot dead by police officers across the country, enflaming public opinion and exposing America’s racial faultlines.
Tensions were raised further by Mr Wilson’s first interview since the shooting in August. He told ABC News there was nothing he could have done differently.
“The reason I have a clean conscience is that I know I did my job right,” he said.
Jay Nixon, the Missouri governor, said the National Guard force in the Ferguson area had been be tripled to more than 2,000 troops to back up a beleaguered local police force and head off a second night of violence.
“Lives and property must be protected. This community deserves to have peace,” he said, as anger mounted nationwide.
After a tense day, protesters clashed with police at about 11pm. A squad car was set alight and bricks were thrown at police lines.
Elsewhere the day passed off peacefully with demonstrations in other major US cities, from Los Angeles to Baltimore, and Chicago, Minneapolis, Philadelphia and Washington. CNN reported protests in 170 cities across 37 states.
In Seattle, hundreds of students walked out of high school classes and rallied at the University of Washington or marched to the downtown federal courthouse.
A woman was injured in Minneapolis when a car ploughed through protesters blocking the road.
© Associated Press Ferguson protests In each city, protesters had their own example of police brutality.
Demonstrators in Cleveland demanded justice for Tamir Rice, a 12-year-old boy who died at the weekend after being shot as he held a replica hand gun .
They marched down an exit ramp and temporarily blocked rush-hour traffic on a busy freeway as police officers stood back.
In New York, relatives of Eric Garner, who died in a police “choke hold” in July, gathered to express their solidarity with the Brown family.
A huge crowd assembled in Manhattan, blocking a key tunnel and creating gridlock before moving on.
They chanted: “Indict, convict, send those killer cops to jail! The whole damn system is guilty as hell!”
One man was arrested for throwing a jar of fake blood that struck William Bratton, the police commissioner.
Many of the demonstrations were organised by the National Action Network, led by Al Sharpton, the veteran campaigner.
“We may have lost one round, but the fight is not over,” he said, calling for a nationwide day of protest on Saturday.
The August shooting of Mr Brown sparked weeks of protest and a debate about race relations and military-style police tactics.