NEW YORK — From New York City to San Francisco, thousands and thousands of diverse people united by anger took to the streets for a second straight night protesting a grand jury clearing a white police officer in the chokehold death of an unarmed black man.

Grandparents marched with their grandchildren. Experienced activists stood alongside newcomers. And protesters of all colors chanted slogans.

“We’re under siege and it has to stop,” Harlem resident Judy Edwards said at a rally Thursday in lower Manhattan’s Foley Square.

The 61-year-old black woman was accompanied by her daughter and twin 10-year-old grandchildren, a boy and a girl. She said it was important to her that the children saw a crowd that was racially mixed and diverse in many other ways all insisting upon the same thing — that something must be done.

That was the message, too, in cities across America: Atlanta, Boston, Chicago, Denver, Detroit, Minneapolis Oakland, San Francisco and Washington, D.C., among them. Sign-carrying, chanting demonstrators marched down heavily-traveled streets and shut down highways and bridges. Politicians talked about the need for better police training, body cameras and changes in the grand jury process to restore faith in the legal system.

In New York, Mayor Bill de Blasio — blasted by police union leaders who accused him of not supporting his officers — outlined previously announced plans to teach officers how to communicate better with people on the street.

President Barack Obama also weighed in, saying one of the chief issues at stake is “making sure that people have confidence that police and law enforcement and prosecutors are serving everybody equally.”

But U.S. Rep. Peter King, R-N.Y., told The Associated Press: “The black community is not right to be upset about the ruling. If this were a white person it would have been the same thing.”

Tensions already were high after a grand jury last week cleared an officer in the shooting death of 18-year-old Michael Brown in Ferguson, Mo. Then on Wednesday came the decision that Officer Daniel Pantaleo would not be indicted in the chokehold death of Eric Garner. In both cases the officers were white and the victims were black.

New York demonstrators targeted the city’s major traffic arteries again Thursday. They gathered near the Holland Tunnel, the Manhattan Bridge and on the Westside Highway, temporarily shutting them down. One group converged on the Staten Island Ferry Terminal. Authorities said arrests were made.