The Rev. Martin Luther King Jr. was best known for his role in the civil rights movement and nonviolent protests. His life's work has been honored with a national holiday, schools and public buildings named after him, and a memorial on the National Mall in Washington. Take a look back at the late civil rights leader's defining years. Here, King speaks in Washington in 1968, the year he was assassinated.
King outlines boycott strategies to his advisers and organizers on January 27, 1956. Seated are the Rev. Ralph Abernathy, left, and Rosa Parks, center, who was the catalyst for the protest of bus riders.
King sits for a police mugshot after his arrest for directing a citywide boycott of segregated buses on February 24, 1956.
King stands in front of a bus at the end of the Montgomery bus boycott in Montgomery, Alabama, on December 26, 1956.
King speaks during the Prayer Pilgrimage near the Reflecting Pool in Washington on May 17, 1957.
Accompanied by his wife, Coretta Scott, King leaves Harlem Hospital after being stabbed near the heart on September 20, 1958. The near-fatal incident occurred when he was autographing copies of his book at a Harlem bookstore.
King delivers a sermon at Ebenezer Baptist Church in Atlanta in September 1960.
King, his wife and children, Yolanda, 5, and Martin Luther III, 3, play the piano together in their living room in Atlanta in 1960.
Moderator John McCaffery, left, segregationist editor James J. Kilpatrick and King debate segregation in New York on November 11, 1960.
King addresses a crowd of demonstrators outside the Lincoln Memorial during the March on Washington for Jobs and Freedom in Washington on August 28, 1963. He delivered his famous "I Have a Dream" speech to more than 250,000 people.
President Lyndon B. Johnson talks with King and civil rights leaders at the White House. On July 2, 1964, Johnson signed the Civil Rights Act into law.
King speaks with Malcolm X at a press conference on March 26, 1964.
In 1963, King became the first African-American to be named Time magazine's Man of the Year.
King receives the Nobel Prize for Peace from the president of the Nobel Prize committee, Gunnar Jahn, in Oslo, Norway, on December 10, 1964. At the time he was the youngest person to win the prize.
King and his wife lead a black voting rights march from Selma to Montgomery, Alabama, on March 30, 1965.
King addresses civil rights marchers in Selma in April 1965.
Mississippi patrolmen shove King during the 220-mile "March Against Fear" from Memphis, Tennessee, to Jackson, Mississippi, on June 8, 1966.
King signs the Degree Roll at Newcastle University after receiving an honorary Doctor of Civil Law degree, in Newcastle, England, on November 14, 1967.
King and comedian Bob Hope, right, talk at John F. Kennedy International airport in New York on November 14, 1967.
Dr. Ralph Abernathy, Jesse Jackson and others stand on the balcony of the Lorraine Motel in Memphis, Tennessee, on April 4, 1968, pointing in the direction of the gunshots that killed King, who lies at their feet.
King's body is pictured on April 8, 1968, following his murder in Memphis. His wife, Coretta, led a silent march of 50,000 people through the streets of Memphis before making a televised speech at his funeral.
The statue of King is pictured at a memorial in August 2013 in Washington, as thousands of people gathered to commemorate the 50th anniversary of the March on Washington for Jobs and Freedom, where King gave his "I Have a Dream" speech.