Basketball stars in New York joined nationwide protests against the failure of a US grand jury to indict a white police officer over the death of an unarmed black man after being put in a chokehold.
Cleveland Cavaliers forward LeBron James and other players wore T-shirts emblazoned with Eric Garner's last words, "I can’t breathe," in pre-game warm-ups at the Barclays Center in Brooklyn.
Britain's Prince William and his wife Kate were among thousands who went to see the team play the Brooklyn Nets.
In California, demonstrators blocked a train and a major road, part of continuing night-time protests over the death in July of Mr Garner, a father of six, which happened after police put him in a banned chokehold.
The decision in the Garner case followed a decision by a Missouri grand jury to clear a police officer in the fatal August shooting of an unarmed black teenager, Michael Brown.
In the California college town of Berkeley, near San Francisco, more than 50 people blocked an Amtrak train.
Some lay on the tracks, while others sat on a sofa on the rails.
Several hundred protesters roamed Berkeley streets elsewhere, blocking roads and shutting down a major road.
The demonstrations came a day after police said five people were arrested when a crowd threw rocks and other objects at officers and many stores were looted.
Outside the Barclays Center, a group of about 300 protesters blocked streets.
They chanted, "I can't breathe," in memory of Mr Garner, and "Hands up, don't shoot," a reference to Mr Brown's death in the St Louis suburb of Ferguson.
In downtown Phoenix, about 200 protesters marched to police headquarters over the killing of an unarmed black man by a white officer in what authorities described as a struggle last week.
Protesters demanded that police release the name of the officer involved in the fatal shooting of 34-year-old Rumain Brisbon, a man police suspected of selling drugs.
