One of the last pictures to be taken of Martin Luther King Jr., as he spoke to a mass rally in Memphis, Tennessee, on April 3, 1968, saying he would not halt his plans for a massive demonstration scheduled for April 8 in spite of a federal injunction. #

Civil-rights leader Andrew Young (left) and others stand on the balcony of the Lorraine Motel pointing in the direction of an assailant after the assassination of the civil-rights leader Martin Luther King Jr., who is lying at their feet, in Memphis, Tennessee, on April 4, 1968. #

Thousands of young people march through Times Square in New York on April 5, 1968, bound for City Hall after a rally in Central Park. The demonstrators, both black and white, were protesting the assassination of Martin Luther King Jr. The line stretched some 12 blocks at times as they marched down Broadway. #

Original caption: "April 5, 1968, Memphis, Tennessee. Casket containing the body of slain civil-rights leader Dr. Martin Luther King Jr. is loaded aboard a plane for transport to his home in Atlanta. Mrs. King flew to Memphis aboard the plane but did not disembark while casket was being loaded." #

Original caption: "Memphis, Tennessee. An unidentified woman has difficulty holding back her tears as she watches the casket of slain civil-rights leader, Dr. Martin Luther King Jr., put aboard a plane for transport to his home in Atlanta, Georgia." #

Scene at Civic Center Plaza in San Francisco, California, on April 5, 1968, as a memorial service was held in memory of slain civil-rights leader Martin Luther King Jr. #

An aerial view showing clouds of smoke rising from burning buildings in northeast Washington, D.C., on April 5, 1968. The fires resulted from rioting and demonstrations after the assassination of Martin Luther King Jr. #

Firemen battle a blaze on 125th Street in Harlem, New York, on April 4, 1968, after a furniture store and other buildings were set on fire after it was learned that civil-rights leader Martin Luther King Jr. had been assassinated. #

President Johnson called federal troops into the nation's capital to restore peace after a day of arson, looting, and violence on April 5, 1968. Here, a trooper stands guard in the street as another (left) patrols a completely demolished building. #

Tear gas, illuminated by street lights, fills the air as police wearing gas masks await possible further trouble in an African American area of northwest Washington, D.C., on April 5, 1968. #

A soldier and civilians walk near a destroyed newsstand at 14th and Kenyon Streets in northwest Washington, D.C., on April 6, 1968, following rioting after the assassination of Martin Luther King Jr. #

For comparison, a print of the previous photo of looted and burned buildings in 1968 is placed on an easel at the present-day shopping area near 14th and Kenyon Streets in northwest Washington, D.C., on March 25, 2018. #

Firemen gather around a fire engine near the intersection of 14th and Irving Streets in Washington, D.C., on April 6, 1968, following rioting after the assassination of Martin Luther King Jr. #

A pedestrian is waved away from an area by a gas-masked national guard soldier guarding an area near 7th and K Streets in northwest Washington, D.C., as rioting continued in the city on April 6, 1968. #

A major fire in Newark, New Jersey, drew a large crowd of onlookers watching firemen pour water onto the burning building on April 6, 1968. City officials had reported some firebomb incidents in response to the assassination of Martin Luther King Jr. #

More than 2,000 paratroopers of the 82nd Airborne Division were flown into Washington, D.C., on April 6, 1968, to augment the federal and national guard units already on duty in riot-torn sections of the city. #

An Illinois national guardsman checks a 30-caliber machine gun mounted on the back of a jeep, as flames blaze in the background on Chicago’s West Side, on April 6, 1968. The area was the scene of fires, looting, and shooting with at least eight deaths resulting from the incident. #

Coretta Scott King, widow of slain civil-rights leader Martin Luther King Jr., wearing a black suit and hat, grieves between the line of mourners waiting to view his body as it lies in state at Sister's Chapel at Spelman College in Atlanta, Georgia, on April 7, 1968. #

Original caption: "Washington, D.C. Fatigued troops in violence-torn Washington tiredly sack out on the floor of a laundromat here. Several of the soldiers had to find sleeping space on top of the washing machines. More than 12,000 troops were called out to protect the nation's capital since the assassination of Martin Luther King Jr. #

Soldiers attend a memorial service for slain civil-rights leader Martin Luther King Jr. in Danang, Vietnam, on April 8, 1968. The chaplain eulogized King as “America’s voice for the wisdom of non-violence,” and deplored the violence following his death. #

Floyd McKissick, head of CORE, addresses a crowd of garment-district workers who stopped work to attend a memorial meeting for Martin Luther King Jr. at Seventh Avenue and 37th Street in New York, April 8, 1968. McKissick told the crowd, "The reason you're here today is because of an act of violence." #

Coretta Scott King, the widow of Martin Luther King Jr., walks on the arm of Dr. Ralph Abernathy, her husband's successor as head of the Southern Christian Leadership conference, leading about 10,000 people in a memorial march in King's honor. The King children—Yolanda, Martin III, and Dexter—are at left with Harry Belafonte. Reverend Andrew Young marches next to Dr. Abernathy. #

Original caption: "Ebenezer Baptist Church, where people came in great numbers to pay respects to fallen leader, Dr. Martin Luther King Jr., on April 8, 1968, in Atlanta, Georgia." #

Rows of Pennsylvania national guardsmen march down the street and sidewalks clearing the area in Pittsburgh's Hill District on April 8, 1968. Residents lean from windows watching the show of force. The guardsmen were called out to restore order following three days of arson and looting in the district. #

A brace of plow mules draw a farm wagon bearing the mahogany casket of Martin Luther King Jr. along the funeral-procession route in Atlanta, Georgia, on April 9, 1968. #

Original caption: "A huge portrait of slain civil-rights leader Dr. Martin Luther King Jr. is held up by marchers during his funeral procession on April 9, 1968. More than 50,000 blacks and whites mingled in the tribute to the advocate of racial progress through nonviolence who was killed by a sniper's bullet." #