Pictured: Dr. Martin Luther King, Jr. delivers his "I have a dream" speech in front of the Lincoln Memorial in Washington. Actor-singer Sammy Davis Jr. is at bottom right.
U.S. President Lyndon B. Johnson reaches to shake hands with Dr. Martin Luther King Jr. after signing the Civil Rights Act of 1964, which outlawed major forms of discrimination against women and racial, ethnic, national and religious minorities (AP photo).
President Lyndon Johnson, surrounded by members of Congress, signs the Voting Rights Act of 1965 two years after the March on Washington. In the back left, looking away from the president, is associate press secretary Harold Pachios of Cape Elizabeth, a founding partner at Portland law firm Preti Flaherty (Photo by Robert L. Knudsen, White House photographer).
Brooke is elected to the U.S. Senate to represent Massachusetts, the first African-American senator since Reconstruction. Pictured is Senator-elect Edward W. Brooke (standing) with a volunteer worker in his Boston headquarters the day after election, Nov. 9, 1966 (AP photo).
The Supreme Court strikes down bans on interracial marriage under a challenge from plaintiffs Mildred and Richard Loving, pictured in this Jan. 26, 1965, file photograph (AP photo).
King's death would provoke riots in Chicago, Washington, Baltimore, and several other major cities. Pictured is an April 7 funeral march coming down Congress Street in downtown Portland (Press Herald file photo by John Olson/staff photographer).
Tommy Smith, center, and John Carlos wear black gloves on upraised right hands as they bow their heads during the playing of U.S. National Anthem in Mexico City on Oct. 16, 1968. The gesture was intended to show their disfavor with race conditions in the U.S. Both of the top finishers in the 200-meter dash were expelled from Olympic Village for the gesture (AP photo).
Una Richardson, one of only two black students in the Deering High School Class of 1971, unsuccessfully appeals to her classmates not to hold their prom at the whites-only Elks club. The Portland chapter of the NAACP stages a demonstration outside of the event in protest (pictured).
After the 1971 Swann v. Charlotte-Mecklenburg Board of Education Supreme Court case, school buses become controversial tools for increasing diversity in public schools, in spite of segregated neighborhoods.
In this September 1974 file photo an unidentified girl is taken into police custody after she threw a rock at a school bus carrying African-American students as it left South Boston High School (AP).
Photo: people view the new Martin Luther King Jr. Memorial in Washington, D.C., on August 22, 2011. The memorial was dedicated in 2011, on the 48th anniversary of the 1963 March on Washington and King’s famous “I Have a Dream” speech (AP).
Federal minimum sentencing laws established in the early 1980s for minor drug offenses would lead to an explosion of the prison population. The number of people incarcerated in federal prisons increased from 24,000 in 1980 to 219,000 in 2013, and estimates from the Pew Charitable Trusts indicate that roughly 1 in 12 African-American working-aged men are currently behind bars.
Four white police officers are videotaped beating Rodney King on March 3, 1991 in Los Angeles. When the officers are acquitted of assault charges on April 29, 1992, riots break out across the city.
The incident leads to reforms at the Los Angeles Police Department and the ouster of police chief Daryl F. Gates. Today, 64 percent of LAPD officers are minorities, compared to 41 percent in 1992.
Barack Obama becomes inaugurated as the first African-American president.
50 years after the March on Washington, debates over racial prejudice are anything but settled on issues ranging from the Trayvon Martin killing to New York City's "stop and frisk" policy.