enlarge The Associated Press

President Barack Obama delivers his inaugural address Tuesday at the U.S. Capitol.

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A man shoots video amid the crowd of more than 1 million on the National Mall on Tuesday.

WASHINGTON — Before a jubilant crowd of more than a million people, Barack Obama claimed his place in history Tuesday, summoning a dispirited nation to unite in hope against the "gathering clouds and raging storms" of war and economic woe.

On an extraordinary day in the life of America, people of all colors and ages waited for hours in frigid temperatures to witness a young black man with a foreign-sounding name take command of a nation founded by slaveholders.

"We gather because we have chosen hope over fear, unity of purpose over conflict and discord," the nation's 44th president said.

The presidency passed to Obama from Republican George W. Bush at the stroke of noon, marking one of democracy's greatest gifts: the peaceful transfer of power.

But it was a stark transfer all the same. In one of the new administration's first acts, Obama ordered federal agencies to halt all pending regulations until further review.

And even though new White House aides struggled to find offices and work intercoms, an overhauled www.whitehouse.gov Web site was running under Obama's banner within minutes of his swearing-in ceremony. "Change has come to America," it declared.

Obama will plunge into his new job in earnest today after capping inaugural festivities at a national prayer service in the morning, meeting with his economic team and Iraq advisers, and welcoming a stream of public visitors into the White House.

The new president had been buoyant and relaxed through the three days of pre-inaugural festivities, but he seemed somber as he stood on the Capitol steps, placed his left hand on the Bible used by Abraham Lincoln and repeated the inaugural oath "to preserve, protect and defend" a Constitution that originally defined blacks as three-fifths of a person.

A deafening cheer went up.

"What is required of us now is a new era of responsibility -- a recognition, on the part of every American, that we have duties to ourselves, our nation and the world, duties that we do not grudgingly accept but rather seize gladly," Obama said. "This is the price and the promise of citizenship."

On the inaugural parade route, Obama and his wife, Michelle, climbed out of the heavily armored presidential limousine and walked a few blocks along famed Pennsylvania Avenue, waving to adoring crowds under the watchful eyes of security agents.

Obama wove a thread of personal responsibility and accountability through his inaugural address, an 18-minute sermon on civic duty. A liberal Democrat proposing billions of dollars in new spending, Obama nonetheless spoke of the limits of government.

"It is the kindness to take in a stranger when the levees break, the selflessness of workers who would rather cut their hours than see a friend lose their job, which sees us through our darkest hours," he said. "It is the firefighter's courage to storm a stairway filled with smoke, but also a parent's willingness to nurture a child, that finally decides our fate."

Obama's 10-year-old daughter, Malia, aimed a camera at her father as he spoke. Michelle leaned onto the edge of her seat, body tensed and brow knitted.

"Starting today, we must pick ourselves up, dust ourselves off and begin again the work of remaking America," Obama said.

He placed blame for the recent economic collapse not just on greed and irresponsibility "on the part of some," but also on the inability or unwillingness of everyone to move the country beyond an industrial-based economy -- what he called "our collective failure to make hard choices and prepare the nation for a new age."

With that, the 47-year-old former senator transformed himself from a candidate claiming his campaign is about the voters to a president promising to put the nation in the people's hands.

Unlike most predecessors, Obama takes office with his agenda in many ways set for him. More inspirational than prescriptive,...