At gatherings across the nation, activists, residents and teachers honored the late civil rights leader on what would have been his 89th birthday and ahead of the 50th anniversary of his assassination in Memphis, Tennessee. In New York City, prominent lawmakers and community leaders took aim at Trump's racial rhetoric.
The event was led by the Rev. Al Sharpton, who spoke to a crowd of 200 at the National Action Network in Harlem on Monday.
"Trump Tower is in the wrong state," said Sharpton, adding that it's embarrassing that the Republican president is from New York.
The audience included Kharey Wise, one of the Central Park Five, who as teenagers went to prison for the brutal 1989 attack on a jogger but were later exonerated by DNA evidence. Trump had called for Wise to be executed, Sharpton said.
"What we're going to do about Donald Trump is going to be the spirit of Martin Luther King Day," he said.
The impassioned audience also heard from Democratic New York politicians, including Gov. Andrew Cuomo, Mayor Bill de Blasio and U.S. Sen. Chuck Schumer. U.S. Sen. Kirsten Gillibrand got a standing ovation after reciting King's writing.
"As tough as these times can be, we have the gift that Dr. King left us," de Blasio said. "He believed it was about us. If you don't like what is happening in Washington, live as Dr. King did."
Trump marked his first MLK Day largely out of sight, buffeted by accusations he used a racially tinged word to describe African countries and scoffed at the suggestion of admitting more Haitians to the U.S. He defended himself Sunday night, declaring, "I'm not a racist."
Again Monday, the president denied making the remarks, saying Democratic Senator Dick Durbin "totally misrepresented what was said at the DACA meeting".
Georgia Congressman John Lewis, himself a Civil Rights icon who knew King personally, told ABC's George Stephanopolous, "I think he is a racist," when referring to President Trump.
"It's unreal," he said. "It's unbelievable. It makes me sad. I think this man, this president, is taking us back to another place."
Martin Luther King Jr.'s children and the pastor of an Atlanta church where he preached decried Trump's remarks Monday, while protests between Haitian immigrants and Trump supporters broke out near the president's Florida resort.
In Washington, King's eldest son, Martin Luther King III, criticized Trump, saying, "When a president insists that our nation needs more citizens from white states like Norway, I don't even think we need to spend any time even talking about what it says and what it is."
He added, "We got to find a way to work on this man's heart."
In Atlanta, King's daughter, the Rev. Bernice King, told hundreds of people who packed the pews of the Ebenezer Baptist Church that they "cannot allow the nations of the world to embrace the words that come from our president as a reflection of the true spirit of America."
"We are one people, one nation, one blood, one destiny...All of civilization and humanity originated from the soils of Africa," Bernice King said. "Our collective voice in this hour must always be louder than the one who sometimes does not reflect the legacy of my father."
Church pastor the Rev. Raphael Warnock also took issue with Trump's campaign slogan to "Make America Great Again."
Warnock said he thinks America "is already great...in large measure because of Africa and African people."
Down the street from Trump's Mar-a-Lago retreat in Palm Beach, Florida, on Monday, Haitian protesters and Trump supporters yelled at each other from opposing corners. Trump was staying at the resort for the Martin Luther King Jr. holiday weekend. Video posted by WPEC-TV showed several hundred pro-Haiti demonstrators yelling from one side of the street Monday while waving Haitian flags. The Haitians and their supporters shouted "Our country is not a s***hole."
The smaller pro-Trump contingent waved American flags and campaign posters and yelled "Trump is making America great again." One man could be seen telling the Haitians to leave the country. Police kept the sides apart.
In Oklahoma, the Cherokee Nation tribe - one of the country's largest - marked the King holiday on Monday with calls to service and by confronting its slave-owning past. A federal court ruled last year that the descendants of former slaves, known as Freedmen, had the same rights to tribal citizenship, voting, health care and housing as blood-line Cherokees.
"The time is now to deal with it and talk about it," said Cherokee Secretary of State Chuck Hoskin Jr. "It's been a positive thing for our country to reconcile that during Dr. King's era, and it's going to be a positive thing for Cherokees to talk about that history as part of reconciling our history with slavery."
One descendant of Freedmen, Rodslen Brown-King, said her mother was able to vote as a Cherokee for the first and only time recently. Other relatives died before getting the benefits that come with tribal citizenship, including a 34-year-old nephew with stomach cancer, she said.
"He was waiting on this decision," said Brown-King, of Fort Gibson, Oklahoma. "It's just a lot of struggle, a lot of up and down trauma in our lives. It's exciting to know we are coming together and moving forward in this."
(The Associated Press contributed to this report)
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