Protest marches have sprang up across the United States, and police battled to stifle another night of unrest in Ferguson, ground zero of America's latest racially-charged riots.
Violence erupted in the St Louis, Missouri suburb for a second night, after Monday's decision by a grand jury not to prosecute a white police officer for shooting dead an unarmed black teenager in August.
Windows were smashed at city hall, a police car was set on fire and protesters pelted police with rocks, bottles, chunks of concrete and a Molotov cocktail, St Louis County police said.
Demonstrators also threw bottles appearing to contain urine, said county police chief Jon Belmar. He said 44 arrests were made, but that in general the night was calmer than Monday, when the town saw rampaging looters, much gunfire from rioters and at least 12 buildings set on fire.
This time police only used tear gas once, Belmar said.
"I think generally it was a much better night," Belmar told reporters.
Missouri Governor Jay Nixon said the National Guard force in the Ferguson area had been tripled to more than 2,000 troops to back up the beleaguered local police force.
Early in the night at the Ferguson police station riot police dispersed around 100 protesters chanting and waving placards, including one that read: "We will not be silenced."
Crowds were smaller than they had been on Monday. But masked agitators on the fringes of the demonstration clashed with police. Later, the violence worsened.
Meanwhile, thousands of marchers snaked along streets and freeways, disrupting traffic on bridges and in tunnels in New York City -- leading to a number of arrests.
A peaceful crowd took to the streets in Washington outside the White House.
Similar angry but largely peaceful protests took place across the country, from Oakland and Seattle on the west coast to Atlanta, Philadelphia and Baltimore in the east.
In sprawling Los Angeles, dozens of protesters were arrested by riot police, the Los Angeles Times reported.
In Portland and Denver police reportedly resorted to pepper spray.
CNN reported that gatherings large and small had been reported in 170 communities nationwide.
