Large crowds are expected to protest in Washington DC against racism and police brutality, amid rising anger in the US sparked by the death of George Floyd.
Mr Floyd died in Minneapolis on 25 May, after a policeman knelt on his neck even as he said he could not breathe.
There have been protests nationwide since, but Washington's police chief believes Saturday's "may be one of the largest we've ever had in the city".
Anti-racism rallies have also been taking place in other countries.
Parliament Square in central London was filled with people supporting the Black Lives Matter movement, despite calls by the British government to avoid mass gatherings for fear of spreading the coronavirus.
In Australia, there were major protests in the cities of Sydney, Melbourne and Brisbane that focused on the treatment of indigenous Australians.
Mr Floyd, an unarmed black man, died after being arrested by police outside a shop.
Video footage showed a white officer, Derek Chauvin, kneeling on Mr Floyd's neck for almost nine minutes while he is pinned to the floor. Mr Floyd is heard repeatedly saying "I can't breathe".
Mr Chauvin has been dismissed and charged with murder. Three other officers who were on the scene have also been sacked and charged with aiding and abetting the crime.
What is planned in Washington?
Some activists have called for a million people to attend the demonstrations in the US capital.
"We have a lot of public, open source information to suggest that the event on this upcoming Saturday may be one of the largest we've ever had in the city," Metropolitan Police Department Chief Peter Newsham told journalists.
He did not provide a crowd estimate, but Army Secretary Ryan McCarthy said local officials were projecting that between 100,000 and 200,000 people would attend.
On Friday, Washington Mayor Muriel Bowser, who has clashed with President Donald Trump over his handling of the protests triggered by Mr Floyd's death, asked for the withdrawal of all federal law enforcement officers and National Guard troops from the city's streets.
In recent days, it had become apparent that their presence was "unnecessary" and "may counterproductive to ensuring the protesters remain peaceful", she said.
Ms Bowser also renamed as Black Lives Matter Plaza an area opposite the White House where federal officers fired smoke grenades to clear protesters ahead of a visit to a church by Mr Trump on Monday.
City workers painted "Black Lives Matter" in large yellow letters on the ground.
More on George Floyd's death
What do protesters want?
An end to police brutality is undoubtedly at the forefront of protests nationwide.
But it isn't the only concern. Repeated incidents of police brutality may have become the flashpoint, but issues with law enforcement are emblematic of the wider problem of systemic racism and inequality.
On social media and on the streets, those in support of the movement have called on elected officials to address these longstanding inequalities, from law enforcement to mass incarceration to healthcare.
Black Americans are jailed at five times the rate of white Americans and they are sentenced for drug offences six times more, often despite equal rates of drug use, according to the NAACP. Black mothers die in childbirth at over twice the rate of white mothers, according to national health data.
Decades of government-sanctioned segregation have also seen inequalities across school systems, housing and other public resources.
A 2019 Pew Research Center study found more than eight-in-10 black adults say the legacy of slavery still affects black Americans' position today. Half say it is unlikely America will ever see true racial equality.
As demonstrator Kyla Berges told BBC Minute: "The system has failed me for 300 plus years, so what do I have to do to make it change?"
What else is happening in the US?
A memorial service will be held in Raeford, North Carolina, near where George Floyd was born.
A public viewing of Mr Floyd's body is being held at a church, after which members of his family will gather for the service.
North Carolina Governor Roy Cooper has ordered that flags be flown at half-mast from sunrise to sunset on Saturday in Mr Floyd's honour.
In Buffalo, two police officers have been charged with second-degree assault after they were filmed pushing an elderly protester to the ground, seriously injuring him.
The officers, who pleaded not guilty and were released without bail, were suspended without pay after footage of the incident went viral on Thursday. Fifty-seven of their colleagues resigned from the Buffalo Police Department's Emergency Response Team in response to their suspension.
On Friday, the Minneapolis City Council and the Minnesota Department of Human Rights agreed to ban police neck restraints and chokeholds.
California Governor Gavin Newsom also said he would move to end state police training in the use of the "carotid restraint".
Seattle's mayor, Carmen Best, meanwhile banned the use by police of CS gas against protesters. And a federal judge in Denver ordered police to stop the use of tear gas, plastic bullets and other non-lethal force.
In separate development, the National Football League reversed its policy on protests against racial injustice by players during the national anthem.
"We were wrong for not listening to NFL players earlier and encourage all to speak out and peacefully protest," Commissioner Roger Goodell said.
US protests timeline
George Floyd dies after being arrested by police outside a shop in Minneapolis, Minnesota. Footage shows a white officer, Derek Chauvin, kneeling on Mr Floyds neck for several minutes while he is pinned to the floor. Mr Floyd is heard repeatedly saying "I cant breathe". He is pronounced dead later in hospital.
Four officers involved in the arrest of George Floyd are fired. Protests begin as the video of the arrest is shared widely on social media. Hundreds of demonstrators take to the streets of Minneapolis and vandalise police cars and the police station with graffiti.
Protests spread to other cities including Memphis and Los Angeles. In some places, like Portland, Oregon, protesters lie in the road, chanting "I cant breathe". Demonstrators again gather around the police station in Minneapolis where the officers involved in George Floyds arrest were based and set fire to it. The building is evacuated and police retreat.
President Trump blames the violence on a lack of leadership in Minneapolis and threatens to send in the National Guard in a tweet. He follows it up in a second tweet with a warning "when the looting starts, the shooting starts". The second tweet is hidden by Twitter for "glorifying violence".
A CNN reporter, Omar Jimenez, is arrested while covering the Minneapolis protest. Mr Jimenez was reporting live when police officers handcuffed him. A few minutes later several of his colleagues are also arrested. They are all later released once they are confirmed to be members of the media.
Derek Chauvin charged with murder