Cities across the United States honored King with ceremonies and performances, as well as reflections on what today's civil rights advocates can do to carry forward his legacy 50 years after his death.
King's eldest son, Martin III, said that recent movements, including Black Lives Matter, #MeToo
and the campaign against gun violence, led by students who survived a school shooting in Parkland, Florida, give him hope.
"I think that Dad and Mom would be very proud to see this group exists," he said of the youth activism.
King's youngest child, Bernice, told CNN's Wolf Blitzer that her father would be making connections with these movements, ensuring they got what they needed in terms of planning and organizational strategy.
Eleanor Holmes Norton, Washington's nonvoting delegate to Congress, said at a wreath-laying ceremony at his memorial near the National Mall that King would want people to focus on the "here and now."
Perhaps the grandest, most-sweeping memorial was in Memphis, where King was slain while standing on the balcony of the Lorraine Motel.
The daylong tribute there -- which featured
speeches, videos, and singing and spoken-word performances -- was largely held
in the courtyard of the motel, now home to the National Civil Rights Museum
Some people at the event held signs reading, "I am a man." They were reminiscent of the signs carried in 1968 in that city by sanitation workers whose strike King had come to support.
The Rev. Jesse Jackson -- one of only two surviving members of King's entourage
on the day he was shot -- was among the speakers at the Memphis tribute.
Here's a look at some of the events that took place to honor King's legacy:
A commemorative ceremony on the balcony of the Lorraine Motel included an interfaith liturgy, musical tributes, and a ceremonial changing of the wreath outside Room 306.
The Rev. Michael Pfleger
, a Catholic priest and activist against street violence on Chicago's South Side, told the crowd that King's "loyalty was to God, and his faith is what summoned him to his activism."
"Dr. King was uncompromising in his commitment to eradicate war and racism and poverty, Pfleger said.
"Martin Luther King Jr. was uncompromising in his charge to subpoena the conscience of America, and demand that America stand before the seat of morality and face her hypocrisy and make good on the promises that she put down on paper," he added.
Pfleger said King believed the church ought to be "dangerous, dangerous to evil, dangerous to injustice."
So, as King stood on a motel balcony, "evil and the forces of hate sought to stop him and shut him up only to find out that a bullet could silence his voice but not his message, nor the truth that lived in him," Pfleger said.
The activist challenged the crowd to not just simply remember King and "relegate his life to some nostalgic or historic event, and then continue on with business as usual."
"Because if we do, then we become the present day co-conspirators of his assassination."
As he wrapped up his speech, the bell from the historic Clayborn Temple
rang 39 times as part of the International Moment of Reflection. Then, a person in the crowd yelled, "Let freedom ring."
When the bell stopped ringing, Pfleger
and Jackson helped place a red and yellow wreath on the balcony.
Later on Wednesday, an "evening of storytelling
" was held at the nearby Crosstown Concourse. Featuring civil rights leaders such as Jackson, it explored how past activism has fed into current movements.
In the city of his birth, the Martin Luther King Jr. Nonviolent Peace Prize was awarded to lawyers Benjamin Ferencz, for his work prosecuting German Nazi leaders at Nuremberg, and Bryan Stevenson, for his work to make mandatory life-without-parole sentences for all children 17 or younger unconstitutional.
Civil rights attorney Benjamin Crump
Stevenson as someone who "shines like a beacon in the dark."
The Ebenezer Baptist Church
choir sang the National Anthem and "Lift Every Voice and Sing" before a game between the Washington Nationals and the host Atlanta Braves.
Members of King's fraternity, Alpha Phi Alpha, attended a service at the historic Ebenezer and carried a wreath into the sanctuary. King joined the black fraternity in 1952 as a Boston University student.
"He took everything we are and wrapped a cloak of courage around it," Greg Gray, a fraternity leader in the Atlanta area, said during the service.
Bernice King addressed the church from the pulpit, describing her father's work.
"My father fought his entire life to ensure the inclusion of all," she said. "He fought for justice and equality and peace."
She said her late mother, Coretta Scott King, "helped to shape and define that legacy so that the world would remember his teachings."
Bernice King recited the closing of King's famous "Mountaintop" speech he gave in Memphis the night before he was killed. "Mine eyes have seen the glory
of the coming of the Lord," she concluded.
At the King Center next door, Elvera Louise Winston and her daughter, Susan Michelle Winston, both of Lithonia, Georgia also praised King's widow. "Coretta kept the legacy going," said Elvera, 71.
Elvera, who lived most of her life in the Chicago and Indiana area, said her parents raised her to know about King.
"He has been with me all my life," she said.
Her mother was from Alabama, where blacks could not use water fountains during the Jim Crow era, Elvera recalled. "All the rules changed mostly because of Martin Luther King," she said.
At the King Center,
members of his family placed a wreath at the crypts of King and his widow, Coretta Scott King, and pulled the bell rope.
Events in the nation's capital started with a morning prayer vigil at the Martin Luther King Jr. Memorial
A silent march then took place from the King memorial to the National Mall, site of the hours-long ACT to End Racism Rally
, which featured speakers, including religious leaders, artists, and activists.