Updated at 4:30 p.m. ET
President Obama, speaking in Selma, Ala., at an event marking the 50th anniversary of the "Bloody Sunday" civil rights march that witnessed hundreds of demonstrators attacked and beaten by police, said the nation was much closer to racial equality, but that the march is not over yet.
"There are places, and moments in America where this nation's destiny has been decided," the president said at the Edmund Pettus Bridge, where Alabama state troopers converged on protesters on March 7, 1965.
"Selma is such a place," he said.
"In one afternoon 50 years ago, so much of our turbulent history – the stain of slavery and anguish of civil war; the yoke of segregation and tyranny of Jim Crow; the death of four little girls in Birmingham, and the dream of a Baptist preacher – all that history met on this bridge," Obama told those gathered, including former President George W. Bush, Rep. John Lewis of Georgia, an Alabama native who was among the marchers and about 100 other members of Congress.
Charter buses from around the country brought thousands into the Alabama town of about 20,000 on Saturday for a day of commemoration and speeches. After the speech, the president and first lady walked over the historic bridge.
"Bloody Sunday" was one of a series of Selma to Montgomery protests in March 1965 organized by civil rights groups, including the Southern Christian Leadership Conference (SCLC) and the Student Nonviolent Coordinating Committee (SNCC). It is viewed as a watershed in the Civil Rights Movement.
In his speech, Obama praised "generations of citizens who believed that America is a constant work in progress; who believed that loving this country requires more than singing its praises or avoiding uncomfortable truths. It requires the occasional disruption, the willingness to speak out for what's right and shake up the status quo."
He referred to racial tensions that have erupted in recent months, speaking directly of the fatal police shooting of Michael Brown last year in Ferguson, Mo., which sparked civil unrest and a crackdown by authorities in the St. Louis suburb. But the president said he rejected the notion that such events prove that nothing has changed in American with respect to race.
"What happened in Ferguson may not be unique, but it's no longer endemic, it's no longer sanctioned by law and custom; and before the Civil Rights Movement, it most surely was," he said.
The president added that it is a mistake to suggest "that racism is banished, that the work that drew men and women to Selma is complete, and that whatever racial tensions remain are a consequence of those seeking to play the 'race card' for their own purposes."
Americans, he said, "don't accept a free ride for anyone, nor do we believe in equality of outcomes. But we do expect equal opportunity."
But even today, he said "there are laws across this country designed to make it harder for people to vote. As we speak, more of such laws are being proposed. Meanwhile, the Voting Rights Act, the culmination of so much blood and sweat and tears, the product of so much sacrifice in the face of wanton violence, stands weakened, its future subject to partisan rancor."
Five decades after "Bloody Sunday," the march is not finished, he said.
"Two hundred and thirty-nine years after this nation's founding, our union is not yet perfect. But we are getting closer. Our job's easier because somebody already got us through that first mile. Somebody already got us over that bridge," the president said.
"We honor those who walked so we could run. We must run so our children soar. And we will not grow weary. For we believe in the power of an awesome God, and we believe in this country's sacred promise."