Obama remembers King’s ‘I have a dream’ address on 50th anniversary (VIDEO)

Exactly fifty years after Rev. Martin Luther King Jr. gave his famous "I have a dream" speech on the steps of the Lincoln Memorial, the nation's first black president spoke in the same spot as an example of the racial progress that King had hoped to see.

President Barack Obama recalled King's historic address and the March on Washington on Wednesday afternoon.

"On a hot summer day, they assembled here, in our nation's capital, under the shadow of the great emancipator, to offer testimony of injustice, to petition their government for redress and to awaken America's long-slumbering conscience."

"His words," Obama said of King, "belong to the ages, possessing a power and prophecy unmatched in our time."

One of the civil rights era lessons, Obama said, was that "freedom is not given; it must be won through struggle and discipline, persistence and faith."

"Because they marched, the civil rights law was passed. Because they marched, the voting rights law was signed. Because they marched, doors of opportunity and education swung open so their daughters and sons could finally imagine a life for themselves beyond washing somebody else's laundry or shining somebody else's shoes," Obama said.

However, Obama said, their work was not complete, and justice would require vigilance. "The March on Washington teaches us that we are not trapped by the mistakes of history, that we are masters of our fate."

The Washington Post has the full transcript.

The planned commemoration of the seminal 1963 event included a march along a 1.6-mile route through downtown Washington D.C. led by a restored 1960s-era bus.

Wednesday's march was expected to draw more than 100,000 participants.

The original march on August 28, 1963 drew about 250,000 people fighting for jobs and equal rights for black Americans. It has been held up as an example of the power of nonviolent protest; the demands for basic freedoms made by the marchers were enshrined a year later in the Civil Rights Act of 1964.

Obama's speech Wednesday was expected to focus on how far the country has come and how far it still has to go.

"Tomorrow, just like 50 years ago, an African-American man will stand on the steps of the Lincoln Memorial and speak about civil rights and justice. But afterward, he won't visit the White House. He'll go home to the White House," Education Secretary Arne Duncan told the Associated Press on Tuesday.

"That's how far this country has come. A black president is a victory that few could have imagined 50 years ago."

In a radio interview on Tuesday, Obama highlighted some of the advances that the country has made in the past fifty years, including equal rights law and the prevalence of African American elected officials and CEOs.

But he told radio host Tom Joyner that having a black president is not enough.

"When it comes to the economy, when it comes to inequality, when it comes to wealth, when it comes to the challenges that inner cities experience, he would say that we have not made as much progress as the civil and social progress that we’ve made, and that it’s not enough just to have a black President, it’s not enough just to have a black syndicated radio show host," Obama told Joyner.

"And so all I can do on an occasion like this," he said, "is just to celebrate the accomplishments of all of those folks whose shoulders we stand on and then remind people that the work is still out there for us to do, and that we honor his speech but also, more importantly in many ways, the organization of the ordinary people who came out for that speech."

Several other prominent speakers also marked Wednesday's anniversary.

Former Presidents Bill Clinton and Jimmy Carter, as well as civil rights protest hero Rep. John Lewis of Georgia, the only surviving speaker from the original 1963 event, were also scheduled to speak.

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Watch an excerpt from Obama's speech: