As the nation's first black commander in chief, the former senator from Illinois personifies the kind of social progress many Americans never dreamed they would see. But he also confronts political and economic challenges no new president has faced since Franklin Delano Roosevelt in 1933.

A reeling economy, record budget deficits, wars and terrorism leave virtually no time for reflection after Obama is sworn in Tuesday to protect and defend the Constitution.

"FDR didn't have a war and a meltdown in the economy at the same time," said Ron Walters, a University of Maryland political scientist. "These are unprecedented times, except for the Civil War, because we don't know ... with any certainty what the end will be."

Obama's election continues an American story of racial trial and triumph, one that courses through the colonial slave trade, the Civil War and a civil rights movement that reached many of its climactic moments while Obama, 47, was a child.

That Obama's election was celebrated around the globe as much as in the streets of America testifies to what his presidency means beyond its traditional place in this country's psyche and the world's judgment.

Historian Doris Kearns Goodwin says the spontaneous Election Night celebrations here may be rivaled only by Andrew Jackson's ascension as the "people's president" in 1828.

And she said Obama has an asset that Abraham Lincoln, another Illinois senator elected amid crisis, did not have.

"A country that potentially will be united ... behind Obama gives him an enormous reservoir of support that Lincoln simply couldn't count upon," Goodwin said. "In some ways, what (Obama) faces is more akin to Roosevelt in '33, although the scale of the problem was much greater than what we are experiencing right now."

The cultural pulpit Obama occupies is a purely modern creation, a convergence of celebrity, mass communications and 24-hour image shaping. Obama's general election foe, John McCain, ridiculed him as the most famous celebrity in the world, but the cut ran shallow because it was fundamentally true.

Obama's cultural quotient — the People magazine obsessions over which dog he'll choose for his children, Europe's obsession with the new first family — shouldn't be underestimated as Americans seek reassurance and normalcy at home and a more accepted image abroad.

Just five years ago, Obama was known primarily for a singularly powerful moment of eloquence, his speech to the Democratic National Convention in 2004. And he married technology and idealism into the most powerful Internet-based political coalition ever.

But his movement is dispersed, diverse and not known for patience. His age and relatively short political resume invite questions about his readiness for such a moment and where he might lead the country.

"This is very much a generational change era," Walters said. "What does it mean in terms of new values?"

With the nation's security and standard of living at stake, what Obama has accomplished so far and what his election means to the country's progress are mere opening acts to the unknowable era to come.