WASHINGTON -- Barack Hussein Obama became the 44th president of the United States on Tuesday, a confident young leader ushering in a new era with a promise of bold action to lift the country out of the worst economic crisis since the Great Depression.
Taking the oath on the steps of a Capitol built in part by slaves, Obama became the first African-American to reach the pinnacle of American political life, fulfilling at last the full promise of a nation born with the pledge that all men are created equal.
He looked out over a sea of perhaps 2 million people, faces of every color, creased with age and fresh with promise, celebrating a turning point of history and looking eagerly for a new voice and vision to lead the country in a new century.
"Today I say to you that the challenges we face are real. They are serious and they are many," he said in a 19-minute inaugural address that was at turns sober about the nation's problems and uplifting about its prospects. "They will not be met easily or in a short span of time. But know this, America: They will be met."
To his countrymen, he urged "a new era of responsibility," but also a greater role for the government, help for the poor and a stronger hand in regulating private markets, which, he said, "without a watchful eye ... can spin out of control."
To the world, he vowed to protect American security without violating "the rule of law and the rights of man," and to talk even to hostile nations. "We will extend a hand if you are willing to unclench your fist," he said.
To those who threaten the United States, he said, "you cannot outlast us, and we will defeat you."
The man he succeeded, George W. Bush, watched quietly from his seat, his time over and the legacy of the Bush era of 20 years in high office -- his eight years as president and his father's 12 as vice president and president -- now left to history.
The peaceful transfer of power was a majestic reminder of democracy at its finest, marking the public's wish to change course, from one political party to another, from one generation to another. At 47, Obama is the first American president who came of age after the turbulence and divisions of the 1960s and the Vietnam War.
Shortly after he became president at the stroke of noon, Obama placed his hand on the same Bible that Abraham Lincoln used at his 1861 inauguration and, following Chief Justice John G. Roberts, took the oath: "I, Barack Hussein Obama, do solemnly swear that I will execute the office of president of the United States faithfully, and will to the best of my ability preserve, protect and defend the Constitution of the United States."
Obama paused for a second when Roberts placed the word "faithfully" at the wrong spot in the sentence, then repeated it as Roberts had, not as it was written into the Constitution more than 200 years ago, which is "faithfully execute the office."
He finished with the phrase that George Washington added and every president since has used voluntarily: "So help me God."
His wife, Michelle, and his young daughters, Malia and Sasha, stood beside him, smiling broadly. Artillery hailed the man and the moment with a 21-gun salute that echoed through the marbled monuments.
Bush, 62, left office one of the least popular presidents of the last century, economic turmoil the punctuation mark on a disappointing presidency. Eleven million Americans are out of work, and more than $1 trillion in stock values has been wiped out.
Bush's dismal standing with the American people rivaled those of Harry S. Truman when he left office in 1953 and Richard Nixon when he resigned in disgrace in 1974.