"We give Martin Luther King his rightful place among the many Americans honored on the National Mall," President Bush told a crowd of about 5,000.
King's memorial, he said, "will unite the men who declared the promise of America and defended the promise of America with the man who redeemed the promise of America."
The King memorial, slated to open in the spring of 2008, will be the first monument for a civilian and black leader on the large park at Washington's core. It is also probably among the last monuments on the Mall following a 2003 vote in Congress to sharply limit development of the parkland.
The stage in front of the crowd was filled with King's fellow civil rights leaders such as Jesse Jackson, celebrities like Oprah Winfrey, politicians including Illinois Sen. Barack Obama, and three of King's children. A gospel choir sang, and Maya Angelou read poetry. Children read essays they had written about King.
Clinton, who signed legislation in 1996 authorizing the memorial, received a standing ovation from the largely black crowd. He told the crowd of King's commitment to nonviolence and social justice causes such as ending poverty, saying those goals still have not yet been achieved.
"If he were here, he would remind us that the time to do right remains," Clinton said.
The memorial will occupy a four-acre plot on the banks of the Tidal Basin, near the Potomac River. The Jefferson Memorial is across the Tidal Basin, while the Lincoln Memorial lies to the northwest, near the river.
The design is based in part on King's 1963 "I Have a Dream" speech. Before repeating the "Let freedom ring" refrain, King told the crowd, "We will be able to hew out of the mountain of despair a stone of hope."
Visitors will pass through an entryway cut through a massive stone symbolizing the mountain of despair and once inside, will come upon the missing section marking the stone of hope, bearing a carved profile of King. It will be ringed with walls chiseled with King's words that may eventually be the base for a waterfall.
Obama, who has said he is considering a presidential run in 2008, spoke shortly after Bush. He imagined bringing his two young children to the memorial when it is completed and passing through the mountain of despair.
"He never did live to see the promised land from that mountaintop," Obama said. "But he pointed the way for us."
Winfrey credited King and other civil rights leaders with making it possible for her to build her talk show empire.
"It's because of them that I can be heard," she said. "I do not take that for granted, not for one breath."
The memorial was first conceived in 1983 by members of King's fraternity, Alpha Phi Alpha. But it has been beset by delays and fundraising issues — the memorial's foundation still has only $70 million of the estimated $100 million construction cost.
Eugene Williams, a Washington resident and an Alpha Phi Alpha member, said he believed the rest of the money will be found now that people know the memorial will be built.
"Absolutely, it's coming forth," he said of funding. "This is a monument to the fact that no other person in history has done what King has done."
In a seat nearby, Carolyn Jackson of Philadelphia recalled how as an 18-year-old in 1963 she was among the vast crowd who heard King's "I Have a Dream" speech during the March on Washington. With much of the civil rights struggle still ahead, Jackson didn't imagine at the time she would be back on the National Mall again because of King.
But she was back despite the cold and rainy weather, and this time not at a memorial borrowed from another leader.
"It's a full circle for black people in this country," Jackson said.