March on Washington: Thousands of civil rights activists to flood DC streets 57 years after King's 'I have a dream' speech

Civil rights activists are returning to the streets of Washington nearly 60 years after Martin Luther King Jr's "I have a dream" speech, but the tens of thousands expected to gather at the Lincoln Memorial are doing so amid new racial tensions stemming from the deaths of black people while interacting with white police officers.

King's eldest son, Martin Luther King III, and the Rev Al Sharpton will headline the event, which will also hear from family members of African Americans killed by police. Organisers are expecting about 50,000 people to attend.

The event was announced by Mr Sharpton at the funeral of George Floyd, who was killed in police custody in Minneapolis in May. His death began a series of nationwide protests – which spread to European countries including Britain – in support of racial justice.

The march, which officially kicks off on Friday morning with a series of speakers on the steps of the famed memorial to the president who ordered all blacks slaves freed, comes after a white police officer shot and paralysed Jacob Blake in Kenosha, Wisconsin. It remains unclear why police there were attempting to arrest Mr Blake, who was shot in the back seven times while moving away from the officer.

Local law enforcement officials this week announced that Mr Blake told two officers that he had a knife. But video of the incident gives no indication he brandished the weapon or was trying to harm the officer who opened fire as he tried to enter his automobile.

The recent spate of police violence against black men and women this week caused three NBA playoff games to be postponed when players – white and black – on several teams voted to strike. A handful of Major League Baseball teams followed suit in an unprecedented work stoppage over racial tensions.

Activists and others spoke out this week in emotional remarks, demanding changes in policing tactics and broader societal ills they say target blacks.

"It's really so sad. Like, I should just be a coach. And I'm so often reminded of my colour. You know, it's just really sad. We've got to do better. But we've got to demand better," Los Angeles Clippers Coach Doc Rivers told reporters during an emotional press conference before the NBA players' strike.

"We all need to demand better of our law enforcement system that enforces laws unevenly and of our justice system that serves justice unequally. My dad was a cop," Mr Rivers said. "I believe in good cops. We're not trying to defund them and take all their money away. We're trying to get them to protect us, just like they protect everybody else."

With nightly protests, sometimes deadly, like when a man with an AR-15 killed two protesters and injured a third in Kenosha, the situation has become part of the presidential election debate. (Though voters from both parties put issues like the economy, jobs and healthcare above racial equality in multiple polls.)

"The violence we're witnessing is happening under Donald Trump. Not me. It's getting worse, and we know why," Joe Biden, the Democratic presidential nominee, said on Thursday.

"Donald Trump refuses to even acknowledge there is a racial justice problem in America. To solve this problem, first we have to honestly admit the problem," the former vice president said. "But he won't do it. Instead of looking to calm the waters, he adds fuel to every fire. Violence isn't a problem in his eyes – it's a political strategy. And the more of it, the better for him."

But Mr Trump and his ever-loyal No. 2 have sided with police.

"So let me be clear. The violence must stop, whether in Minneapolis, Portland or Kenosha, too many heroes have died defending our freedom to see Americans strike each other down. We will have law and order on the streets of this country for every American of every race and creed and colour," Vice President Mike Pence said during his VP-nomination-acceptance speech on Thursday night.

"President Trump and I know that the men and women who put on the uniform of law enforcement are the best of us," he added, never saying Mr Blake's name. "Every day, when they walk out that door, they consider our lives more important than their own."

But as tensions boil in some US cities, the organisers of Friday's march are urging participants to avoid violent acts.

"We expect all marches to abide by all laws and any instruction of law enforcement," according to the National Action Network. "Finally, we are planning a peaceful demonstration and are training marshals in de-escalation tactics and ask that all marches remain peaceful."