Thousands are expected to gather in Washington DC to commemorate the 1963 civil rights March on Washington and in protest of police violence.
The families of black Americans shot or killed by police will speak at the same site where Martin Luther King Jr delivered his I Have a Dream speech.
Friday’s event is called the Commitment March: Get Your Knee off Our Necks, a reference to George Floyd’s death.
It follows renewed protests over the police shooting of Jacob Blake.
The relatives of Mr Blake, Mr Floyd, Breonna Taylor and Eric Garner are expected to deliver speeches at the march.
They will be joined by civil rights leader Reverend Al Sharpton and Martin Luther King III – the eldest son of Mr King Jr.
The event comes in the wake of at times violent protests over Mr Blake’s shooting that have left two dead in Kenosha, Wisconsin. Mr Blake was shot and injured by police last Sunday.
Democratic vice-presidential nominee Senator Kamala Harris is also expected to address the rally virtually.
Rev Sharpton announced the march – which falls on the 57th anniversary of the 1963 event – at Mr Floyd’s memorial service in June.
His organisation, the National Action Network, worked with Mr King III to convene the march.
Planners said the event will bring together generations for a day of action to advocate for police reform as well as to urge Americans to vote in the upcoming presidential election.
Given Covid-19 concerns, people have been encouraged to participate virtually if they cannot attend or in local marches taking place in other states. In Washington, there will be temperature checks and mandatory masks along with social distancing.