The Rev. Martin Luther King Jr. addresses a crowd near the Lincoln Memorial during the March on Washington for Jobs and Freedom on August 28, 1963. On the 50th anniversary of this historic civil rights event, we take a look back through rarely-seen color photographs from the day. 
Civil rights protesters clap and cheer. An estimated 250,000 people participated in the march. 
Leaders of the rally, including King in the center, interlock hands and arms as they march. The march was organized jointly by James Farmer, of the Congress of Racial Equality; Dr. King, of the Southern Christian Leadership Conference; John Lewis, of the Student Nonviolent Coordinating Committee; A. Philip Randolph, of the Brotherhood of Sleeping Car Porters; Roy Wilkins, of the National Association for the Advancement of Colored People; and Whitney Young, Jr., of the National Urban League. 
Protesters sing at the march. 
A protester sings at the march. 
A demonstrator holds a protest sign at the rally. 
Musician Odetta Holmes plays a song during the march. 
King stands with Rabbi Joachim Prinz, center, by his side. 
The crowd cheers during the event. 
African-American entertainer Sammy Davis Jr. attends the rally. 
Demonstrators crowd together as they listen to civil rights speakers during the rally. 
A woman attends the rally. 
Actor Burt Lancaster speaks to protesters at the Lincoln Memorial at the event. 
Actor Sidney Poitier, left, and Singer Harry Belafonte talk with one another during the march. 
Baseball player Jackie Robinson, right, attends the rally with his son David. 
A. Philip Randolph, who helped organize the rally, stands in front of the Lincoln Memorial. 
Civil rights leaders from left, Whitney Young Jr., Martin Luther King Jr., Walter Reuther, Eugene Carson Blake, and John Lewis stand on the steps of the Lincoln Memorial during the march. 
Demonstrators gather around the National Mall near the Lincoln Memorial before the beginning of the march. 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
- NEW: Crowds gather in Washington to hear Obama and leaders speak
- Obama will commemorate the 50th anniversary of King's "I Have a Dream" speech
- Officials: Obama to strike different tone than the Rev. Martin Luther King Jr. did in 1963
- As the first black president, Obama is seen as a product of the civil rights movement
Watch CNN TV for special coverage throughout the day, including live coverage of President Obama's address at the Lincoln Memorial, marking the 50th anniversary of the March on Washington and Martin Luther King Jr.'s "I Have a Dream" speech.
Washington (CNN) -- Crowds gathered on the National Mall on Wednesday under gray skies and drizzle to hear President Barack Obama -- along with a slate of other speakers, including two former presidents and prominent civil rights leaders -- commemorate the 50th anniversary of the Rev. Martin Luther King Jr.'s "I Have a Dream" speech, representing a symbolic moment in U.S. history.
On that day in 1963, when King and his fellow marchers attended what he labeled "the greatest demonstration for freedom in the history of our nation," few in that crowd could have imagined that half a century later, an African-American president of the United States would mark the occasion with a speech in the same location.
Before Obama addressed the throngs gathered at the Lincoln Memorial, civil rights leaders past and present remembered the decades-long movement to secure equal treatment and rights for African-Americans.
"We marched. We sat. The triumphs, and even defeats, belong to us all," said Myrlie Evers-Williams, widow of slain civil rights leader Medgar Evers. "Dr. King told us that he might not get to the mountaintop with us, but he said there is a promised land and America is that promised land for all us."
Celebrities and entertainers at the event included Forest Whitaker and Oprah Winfrey, who star as husband and wife in one of the summer's hottest movies, "Lee Daniels' The Butler," about life in the White House through the eyes of the (mostly black) hired help.
9 things about MLK's speech and March on Washington
Winfrey declared King had seen injustice and "refused to look the other way."
"We, too, can be courageous by continuing to walk in the footsteps of the path that he forged," Winfrey said.
Two musicians who performed at the 1963 march also sang Wednesday. Peter Yarrow and Paul Stookey, from the trio Peter, Paul and Mary, sang Bob Dylan's "Blowin' in the Wind," backed by Sybrina Fulton and Tracy Martin, the parents of Trayvon Martin, whose 2012 shooting death sparked a national conversation about race. Mary Travers, the third artist in the group, died in 2009.
Obama's most personal remarks on race to date came in the aftermath of the July verdict that found Martin's killer not guilty.
On Wednesday, however, the White House was clearly seeking to keep expectations in check about the president's speech commemorating King, but the time, the place and the fact that King and Obama arguably are the two most important figures in American black history lend themselves to comparisons of the two men.
A White House official told CNN that Obama was still working on the speech late Tuesday but that the president's remarks are expected to honor King and his ideals and not be an attempted "re-creation" of the rousing oration delivered by the legendary Baptist preacher from Atlanta.
10 signposts on America's race journey
The official said the president had spoken to several people about the speech, including Rep. John Lewis, D-Georgia, another important civil rights leader from the 1960s. Lewis is the only remaining speaker from the original 1963 march scheduled to speak at the event Wednesday.
The 50th anniversary celebration is expected to be a parade of the famous and powerful.
Former Presidents Jimmy Carter and Bill Clinton also were attending.
However, neither of the living former Republican presidents was expected to attend. George H.W. Bush and his son George W. Bush both opted out, citing health concerns. The latter is recovering from a recent heart procedure.
Jackson: Obama the product of civil rights movement
The Rev. Jesse L. Jackson, a contemporary of King's who was with him the night he died, sees Obama as the finest product of the modern civil rights movement that began in the mid-1950s.
Obama "is the crown jewel of that movement," Jackson said.
But Jackson also said he sees Obama in a completely different group of leaders from King.
"He is in the category of Lincoln, Roosevelt, Johnson. Dr. King is in the category of Frederick Douglass. Clarence Thomas would be in the category of Thurgood Marshall. We should not confuse his roles to that extent," he said.
The present moment has done more than prompt comparisons between King and Obama.
Opinion: Did we really learn the lesson of the March on Washington?
It has also spurred debate over the "dream" about which King spoke so eloquently. Jackson said there was more than one dream for King and the civil rights movement before his assassination in 1968.
"The dream in '63 was to overcome humiliation. ...The dream of '64 was public accommodations, to make that legal. The dream of '65 was the right to vote. The dream of '66 was fair and open housing. The dream of '67 was a Poor People's campaign and to choose the war on poverty over the war in Vietnam. And he was a very different person in '68 because he was under such attacks ... and he was finally killed."
But to many, the "dream" that King articulated is -- more than anything else -- about racial equality and justice. And the question is how close to the goal we've gotten in a country that just re-elected its first black president.
Social activist Robert Woodson, who heads the Center for Neighborhood Enterprise, said the African-American community faced a completely different set of issues in the 1960s. "Our problems today are not the Klan coming in, but it is, what are we doing to ourselves?"
Woodson added, "About 10 years ago, there was a Klan rally in downtown Washington, and The Washington Post asked an old black guy in (mostly black) Ward 8 -- the highest crime area of the city -- if he was going to join in the demonstration. He said, 'Bring the Klan down here if they can get rid of these drug dealers.' "
Woodson, who is black and describes himself an independent, is highly critical of the current state of civil rights advocacy. He recently addressed a meeting of the Republican National Committee, echoing some of his concerns about the movement and the state of black leadership.
5 faces of the March on Washington
"I really think it has morphed into a race-grievance industry. I think they have descended from the moral high ground that they used to occupy. And that they have become an extension of the Democratic Party," Woodson said.
Some conservatives have criticized the 50th anniversary celebration as an exercise of liberal Democratic politics, though the organizers have said the agenda is nonpartisan.
Organized labor; lesbian, gay, bisexual and transgender groups; and opponents of "stand your ground" laws all see Wednesday's event as an opportunity to get their messages out.
However, many Republicans have chosen to remain on the sidelines.
The only class MLK ever taught
