Barack Obama once described himself as having been "a young man of mixed race, without firm anchor in any particular community, without even a father's steadying hand."

What he did have, he says, was "the American Dream" — the idea that "we are not constrained by the accident of birth, but can make of our lives what we will."

His first challenge was to reach across racial and cultural chasms within his family and himself. Later, as a community organizer in Chicago, Obama, 47, learned to listen to others, to find common ground and to help work toward shared goals.

He has applied those lessons ever since.

America has never chosen a president like Barack Hussein Obama: born in Hawai'i to a white teenage mother and a visiting black student from Kenya, named for the father who left when he was 2, raised in Indonesia and Hawai'i by his mother and her parents.

Obama's father was a distant figure who visited him once when he was 10. He died in a car crash in Nairobi when Obama was 21.

Stanley Ann Dunham, Obama's mother, was an idealistic anthropologist who wore Birkenstocks and spent years abroad promoting credit programs for women.

"She insisted that we engage in a life of service," says Maya Soetoro-Ng, Obama's half sister.

Adolescence in Hawai'i was difficult. Obama wrote that he learned "to slip back and forth between my black and white worlds."

His post-college life began in 1985, at 24, at the church-based Developing Communities Project in Chicago. Jerry Kellman offered him $10,000 a year to organize a South Side neighborhood devastated from plant closings.

"He built it into something strong," Kellman says. "He made sure that when he left, there was something that would survive his leaving."

He also acquired a pastor — Trinity United Church of Christ's Jeremiah Wright — who would later preside at his wedding, baptize his daughters, provide the title of his second book and nearly destroy his presidential campaign.

Obama arrived at Harvard at 27. His election as Harvard Law Review's first black president was so noteworthy that The New York Times wrote an article and a book publisher gave him a contract.

Classmates say Obama kept the peace in a contentious atmosphere.

"When things threatened to blow up, he was a calming force," says law-review colleague Kenneth Mack, now a Harvard law professor.

Obama returned to Chicago to marry another Harvard law graduate, Michelle Robinson. They met at a law firm when she was picked to be his summer mentor.

In 1996, Obama was elected to the Illinois Senate.

"He was a legislative machine" in the state Senate, says David Wilhelm, a former national Democratic Party chairman who until recently lived in Chicago. "He actually cared about ideas and was willing to work hard to make those ideas a reality."

His most notable speech during that period was his 2002 argument against invading Iraq. He said that "even a successful war ... will require a U.S. occupation of undetermined length, at undetermined cost, with undetermined consequences."

Obama's national ascent began at the 2004 Democratic National Convention with a keynote speech about his unusual background and the ties that bind America. He was running for U.S. Senate.

"We worship an awesome God in the blue states, and we don't like federal agents poking around our libraries in the red states," he said. "We coach Little League in the blue states and, yes, we've got some gay friends in the red states."

That November he defeated Republican Alan Keyes, a black conservative recruited from Maryland, by the largest margin in Illinois history: 70 percent to 27 percent.

On Feb. 10, 2007, barely two years after he arrived in Washington, Obama entered the presidential race.

He had bet correctly that change was what voters wanted most, and that the Internet had vast untapped potential as an organizing and fundraising tool. He also had a team that did not discount any state, allowing him to pile up convention delegates in unlikely places like Idaho.

On Election Night, Obama paid tribute to the dream that had sustained him: "If there is anyone out there who still doubts that America is a place where all things are possible ... tonight is your answer."