The pastor and Nobel Peace Prize Winner was slain aged 39 on the balcony of his motel by a white supremacist sniper on Apr 4, 1968.
MEMPHIS: Americans on Wednesday (Apr 4) marked 50 years since the assassination of Martin Luther King Jr, a day seared into the national consciousness that transformed the civil rights leader into a symbol of the fight for racial equality.
In a country still torn over issues of race and class demonstrators rallied in Memphis, Tennessee where the pastor and Nobel Peace Prize Winner was slain aged 39 on the balcony of his motel by a white supremacist sniper on Apr 4, 1968, as well as in Washington where he delivered his historic "I Have a Dream" speech.
"When we look at the state of race relations, we've made dramatic progress in 50 years -- but we're nowhere near where we need to be," King's activist son, Martin Luther King III, told ABC's Good Morning America from Memphis, where he was taking part in a symbolic march.
"I think he'd be disappointed with some of the discourse that we see," said King III, although he added that his father would "be very excited" by today's activist movements including Black Lives Matter, the #MeToo campaign for women's rights, and student-led movements against gun violence.
"He would know that we as a nation can, must and will do better."
Now lionised for his heroic campaigns against racism and segregation, King was a controversial, radical activist who with a mantra of non-violence also ardently campaigned against poverty, income equality and US wars abroad.
call for non-violent action that lives on.
"He was a man of marching, he was a man that was non-violent," the sanitation worker said. "That's what I remember today."
'PROMISED LAND'
US President Donald Trump also paid homage to the civil rights icon by proclaiming Apr 4, 2018 a day to honour King.
"It is not government that will achieve Dr. King's ideals, but rather the people of this great country who will see to it that our Nation represents all that is good and true, and embodies unity, peace, and justice," Trump said in a statement.
Trump has been sharply criticised for divisive comments targeting Mexican and Muslim immigrants, and for refusing to condemn outright a violent white supremacist rally that ended in bloodshed.
Several US lawmakers travelled to Memphis for the day-long tribute featuring singing, prayer and speeches.
Laura Richardson, who works for a non-profit group, said she praised the "courage" within King "to go in love, go without violence, and never take a step back, and fight for everyone's right."
A crowd gathered at the Lorraine Motel, which has been transformed into the National Civil Rights Museum, while more than 1,000 also marched near a local union headquarters, where King had joined protesting workers on the eve of his assassination.
"I've seen the promised land. I may not get there with you," King prophetically said that night. "But I want you to know tonight, that we as a people will get to the promised land!"