WASHINGTON - US cities on Wednesday marked the 50th anniversary of Martin Luther King Jr.'s assassination, with ceremonies and reflection on how to carry forward his legacy.

At the Martin Luther King Jr. Memorial in Washington D.C., crowds gathered to commemorate the late civil rights leader with speeches and flowers.

Washington D.C. Mayor Muriel Bowser said at a wreath-laying ceremony at the memorial that King, who was only 39 when he was killed, should serve as an inspiration for young people everywhere.

"As a young leader, he spoke truth to power. He confronted our country's greatest sins head on," Bowser said. "He changed the world forever."

King was shot and killed at a motel in Memphis, in the state of Tennessee, in 1968, during a trip to the city to protest against the low pay of sanitation workers.

He was leading non-violent protests against inequality during the civil rights movement and won the Nobel Peace Prize in 1964.

Gary Teasley, from Michigan, told Xinhua that he still clearly remembers the day that King was killed. "It was devastating," he said. "We have never really recovered from that."

But Teasley said that King's impact was so powerful that his presence is still felt today.

Surrounding King's statue at the memorial are inscription walls that feature his famous quotations, which attracted the attention of visitors.

Brett Alger, from Maryland, told Xinhua that King's impact "was far beyond his years" and has influenced generations of people. However, Alger admitted that King's goals of racial and economic justice haven't been achieved.

Paying tribute with her friends to King and showing support of activities that call for an end to racism, Brianna Hunter, a sophomore, said that there should be no place for racism, but it still occurs.

In Memphis, a touching day-long tribute was held in the courtyard of the Lorraine Motel, where King was slain while standing on the balcony. It is now home to the National Civil Rights Museum.

After a bell rang 39 times to mark the time that King was gunned down 50 years ago, a red and yellow wreath was placed on the balcony outside Room 306 where King stayed before his assassination.

Senator Bernie Sanders also traveled to Memphis to pay tribute to King.

"He was a non-violent revolutionary," the Vermont lawmaker told a rally. "He was a man who wanted to transform our country morally, economically and racially."

In Atlanta, Georgia, members of his family also laid a wreath at the crypts of King and his widow, Coretta Scott King.

King's daughter Bernice King told CNN that her father's words are still very relevant now. "The legacy he's left for us of non-violent, social change and peace with justice is something that, you know, resonates."

She also said that she hopes that people not only remember her father on this day, but that they also "act in his spirit to bring about the changes that are needed to create a more just, humane and peaceful world."