Elizabeth Eckford ignores the hostile screams and stares of fellow students on her first day of school. She was one of the nine African-American students whose integration into Arkansas' Little Rock Central High School was ordered by a federal court following legal action by the NAACP. September 6, 1957.Bettmann/Contributor/Getty Images
Two terrified African-American girls flee police officers during a race riot in the Bedford-Stuyvesant neighborhood of Brooklyn, itself sparked by rioting over police brutality in nearby Harlem, on July 21, 1964.Bettmann/Contributor/Getty Images
Two young girls join hands while riding the bus together during the initial phases of the integration of the school system in Boston, Massachusetts. September 15, 1975.Bettmann/Contributor/Getty Images
In late July 1964, police beat a man during the Harlem riots sparked by the questionable shooting of a 15-year-old African-American boy by a police officer. Dick DeMarsico/New York World Telegraph & Sun/Library of Congress/Wikimedia Commons
Martin Luther King Jr. speaks at a rally for the Chicago Freedom Movement at Soldier Field in Chicago, Illinois on July 10, 1966.
The movement, the largest civil rights campaign in the North, sought fair housing, healthcare, transportation, and so on for African-Americans.Afro American Newspapers/Gado/Getty Images
Civil rights marchers stay close to the ground as Mississippi Highway Patrolmen use tear gas on the protestors. Canton, Mississippi. June 23, 1966.Hulton Archive/Getty Images
Rosa Parks has her fingerprints taken after being arrested for boycotting public transportation in Montgomery, Alabama. February 1956.Associated Press/Wikimedia Commons
Twelve-year-old Sarah Jean Collins lies in a hospital bed following the bombing of the 16th Street Baptist Church in Birmingham, Alabama on September 15, 1963.
The bombing, carried out by four members of the Ku Klux Klan, killed Collins' sister and three other girls as her Sunday school class was ending.Frank Dandridge/The LIFE Images Collection/Getty Images
On April 3, 1968 at the Mason Temple in Memphis, Martin Luther King Jr. delivers his now famous "I've Been to the Mountaintop" speech to 2,000 people.
This would be the last speech he would ever give. He was assassinated the following day.Bettmann/Contributor via Getty Images
Civil rights leader Andrew Young (left) and others standing on the balcony of Memphis' Lorraine Motel point in the direction of the then unknown assailant just after the fatal bullet struck Martin Luther King Jr., who is lying at their feet. April 4, 1968.Joseph Louw/The LIFE Images Collection/Getty Images
Theatrice Bailey, brother of the Lorraine Motel's owner, scrapes the blood of Martin Luther King Jr. from the motel balcony following King's assassination on that very spot. Memphis, Tennessee. April 4, 1968.Henry Groskinsky/The LIFE Picture Collection/Getty Images
Troops survey the flaming terrain on Washington, D.C.'s Seventh Street on April 6, 1968 amid the rioting caused by the assassination of Martin Luther King Jr. on April 4.Bettmann/Contributor/Getty Images
Seventeen-year-old student John Carter stands outside Clinton High School in Tennessee while holding a sign in protest of integration on August 27, 1956.Bettmann/Contributor/Getty Images
A first-grade girl is escorted by US Federal Marshals to a grade school that is being guarded by city police on the first day of school integration by order of the federal court. New Orleans, Louisiana. November 14, 1960.Underwood Archives/Getty Images
A nervous young girl sits in the front row of her newly desegregated class, in which she is the only African-American. Tennessee. September 1957.Don Cravens/The LIFE Images Collection/Getty Images
In Mexico City on October 17, 1968, American Olympians Tommie Smith (center) and John Carlos (right) raise their gloved fists in the Black Power salute to express their opposition to racism back home during the U.S. national anthem, after receiving their medals for first and third place, respectively, in the men's 200m race.-/AFP/Getty Images
Martin Luther King Jr. and Malcolm X meet for the first and only time following the former's press conference in Washington, D.C. on March 26, 1964.Marion S. Trikosko/U.S. News & World Report/Library of Congress/Wikimedia Commons
Congress of Racial Equality trainees endure an "egg shampoo" exercise in preparation for remaining calm during nonviolent demonstrations. Location unspecified. August 11, 1963.Bettmann/Contributor/Getty Images
Fifteen-year-old Johnny Gray points a warning finger at one of the two white boys who tried to force him and his sister, Mary, from the sidewalk as they walked to school in Little Rock, Arkansas on September 16, 1958.
The argument ended in a fist fight, with Gray chasing the white boys down the block.Bettmann/Contributor/Getty Images
Demonstrators rally in support of jailed civil rights leader Wally Nelson. Location unspecified. Circa 1965.MPI/Stringer/Getty Images
A mob beats Freedom Riders who've arrived at the bus station in Birmingham, Alabama. May 1961.
Bull Connor, head of Birmingham’s police, made a pact with the Klan that the police would stay away from Birmingham’s bus terminal for fifteen minutes after the Freedom Riders arrived, enough time to severely beat some of the Riders into the hospital.
This photo was reclaimed from a local journalist who also was beaten and whose camera was smashed.Federal Bureau of Investigation/National Endowment for the Humanities/Wikimedia Commons
Three demonstrators join hands to build strength against the force of water sprayed by riot police in Birmingham, Alabama, during a protest of segregation practices. May 4, 1963.Bettmann/Contributor/Getty Images
On March 29, 1968 in Memphis, U.S. National Guard troops faced off with Civil Rights marchers wearing placards reading, "I am a man."
This was the third march in as many days. Martin Luther King Jr. had been there on the first day to participate.Bettmann/Contributor/Getty Images
Police subdue a rioter during the third night of race riots in Paterson, New Jersey. August 14, 1964.Bettmann/Contributor/Getty Images
Demonstrators hold signs and join hands during the March on Washington on August 28, 1963.National Archives and Records Administration
Martin Luther King Jr. waves to supporters from the steps of the Lincoln Memorial during the March on Washington, at which he delivered his famous "I Have a Dream" speech on August 28, 1963.-/Stringer/AFP/Getty Images
A civil rights marcher suffering from exposure to tear gas holds an unconscious Amelia Boynton Robinson, noted activist, after mounted police officers attacked marchers in Selma, Alabama as they were beginning a 50-mile march to Montgomery to protest race discrimination in voter registration. March 8, 1965.Bettmann/Contributor/Getty Images
Several African-Americans confront National Guardsmen during the Newark, New Jersey riots in response to police brutality on July 14, 1967. -/AFP/Getty Images
On July 20, 1964 in Harlem, Anna Powell breaks down in tears as she leaves the funeral home following services for her 15-year-old son, James, who had been killed by a policeman four days earlier. His death set off a series of riots in Harlem as demonstrators protested police brutality.Bettmann/Contributor/Getty Images
Police officers watch as jeering students protest desegregation at West End High school in Birmingham, Alabama after two African American students entered the school on September 16, 1963.Bettmann/Contributor/Getty Images
Firemen turn their hose on a group of African-Americans during an anti-segregation demonstration in Birmingham, Alabama on May 3, 1963.Bettmann/Contributor/Getty Images
Students from Pittsburgh, Pennsylvania take part in the March on Washington on August 28, 1963.National Archives and Records Administration
Minnijean Brown, 15, one of the Little Rock Nine, arrives outside Central High School, as members of the 101st Division of the Airborne Command stand ready to protect them, under orders from President Dwight Eisenhower. Little Rock, Arkansas. September 25, 1957.A.Y. Owen/The LIFE Picture Collection/Getty Images
Ku Klux Klan members rally in support of presidential candidate Barry Goldwater amid counterprotesters during the 1964 Republican National Convention in San Francisco, California.Warren K. Leffler/Library of Congress
On May 29, 1968, Washington D.C. police tussle with a demonstrator of the Poor Peoples Campaign for civil rights and poverty relief during a protest at The Supreme Court.Wally McNamee/CORBIS/Corbis via Getty Images
Demonstrators gather in the shadow of the Washington Monument during the March on Washington on August 28, 1963.Marion S. Trikosko/Library of Congress
NAACP student advisors blow smoke into the face of a volunteer demonstrator as part of a tolerance training exercise for nonviolent protests. Petersburg, Virginia. May 1960.Howard Sochurek/The LIFE Picture Collection/Getty Images
Police drag away a civil rights protester at the Republican National Convention in Miami in August 1968.Bettmann/Contributor/Getty Images
The enormous crowd gathers around the Reflecting Pool between the Lincoln Memorial and the Washington Monument for the March on Washington on August 28, 1963.National Archives and Records Administration
Benny Oliver, former Jackson, Mississippi policeman, viciously kicks Memphis Norman, an African-American student from nearby Wiggins who had been waiting along with two other students to be served at a segregated lunch counter. The rumor of possible civil rights actions in the town caused onlookers to cheer the beating. May 28, 1963.Bettmann/Contributor/Getty Images
A Nashville policeman grabs a demonstrator and tells him to move from in front of a patrol wagon during a protest on April 27, 1964.
The young man refused and was subdued by the policemen and thrown into the wagon with other demonstrators just after this photo was taken.Bettmann/Contributor/Getty Images
Civil rights leader Ralph Abernathy (left, behind priest), his children, as well as Mr. and Mrs. Martin Luther King Jr. (behind children) lead the Selma to Montgomery civil rights march through Alabama in March 1965.Abernathy Family/Wikimedia Commons
African-American students arrive at Baltimore, Maryland's newly integrated Southern High School as white students walk behind with a sign reading "Southern don't want negroes." October 4, 1954.Bettmann/Contributor/Getty Images
Two blood-splattered Freedom Riders stand together after being attacked and beaten by pro-segregationists in Montgomery, Alabama on May 20, 1961.
The Freedom Riders were a collective of civil rights activists that rode public buses in the South during the early 1960s in protest of the non-enforcement of mandates that such transportation must be desegregated.Bettmann/Contributor/Getty Images
Two boys work in the Freedom Press Office in Hattiesburg, Mississippi, for the Mississippi Project, a campaign to increase black voter registration in the South. July 24, 1964.© Bettmann/CORBIS/Bettmann Archive/Getty Images
Police officers walk with a police dog that bears its teeth and barks at African-American demonstrators during protests to end racial segregation. Cambridge, Maryland. July 1, 1963.Afro American Newspapers/Gado/Getty Images
Two young protesters try to avoid the blast of a fire hose during a civil rights protest in Birmingham, Alabama on May 7, 1963.Bettmann/Contributor/Getty Images
A police dog attacks an African-American protester during an anti-segregation demonstration in Birmingham, Alabama on May 4, 1963.Afro American Newspapers/Gado/Getty Images
A policeman twists a man's neck in a choke hold during a civil rights demonstration. Location unspecified. Circa 1962.Washington Bureau/Stringer/Getty Images
Police carry a young woman into a patrol wagon during a civil rights demonstration in Brooklyn, New York. 1963.Dick DeMarsico/World Telegram & Sun/Library of Congress
On April 7, 1968, a Pennsylvania National Guardsman patrols a street littered with wreckage from an afternoon of rioting in Pittsburgh following the assassination of Martin Luther King Jr.Bettmann/Contributor/Getty Images
Police subdue a man during the Watts riots in Los Angeles. August 1965.
Upset at racial discrimination and police brutality, the city's African-American population grew further upset after the violent, public arrest of two young African-American men and their mother following a scuffle with police on August 11. Between 31,000 and 35,000 people then took to the streets in riots that left 34 dead, 1,032 injured, 3,438 arrested, and $40 million worth of property damaged.New York World-Telegram/Library of Congress/Wikimedia Commons
Police toss a demonstrator into a mass of protesters that had been rallying at the U.S. Consulate in support of civil rights activists in Alabama. Toronto, Canada. March 16, 1966.Gerry Barker/Toronto Star/Getty Images
Two members of the Black Panther Party are met on the steps of the California State Capitol in Sacramento by Police Lt. Ernest Holloway, who informs them they will be allowed to keep their weapons as long as they cause no trouble and do not disturb the peace. May 2, 1967.Bettmann/Contributor/Getty Images
Two demonstrators sit together, shielding themselves from the sun, during the March on Washington on August 28, 1963.National Archive/Newsmakers/Getty Images