Barack Hussein Obama has taken the oath of office as the 44th president of the United States.
With a hand on Abraham Lincoln's inaugural Bible, and before a crowd stretching across the National Mall toward where Martin Luther King, Jr., spoke of his dream of racial equality, the 47-year-old Obama was sworn in as the first black American president by Chief Justice John Roberts.
Roberts told him, "Congratulations, Mr. President."
Obama's wife, Michelle, and daughters, Sasha and Malia, looked on. They were joined by people from around the world who gathered in huge numbers in the early morning Washington cold to see history made.
In his inaugural speech, President Obama called for a "new era of responsibility" in America.
Near the end of his address, Obama spoke of the need for every American to recognize duties to themselves, their nation and the world.
He called it "the price and the promise of citizenship." And he says it's also the source of the nation's confidence that "God calls on us to shape an uncertain destiny."
Obama told the crowd, "There is nothing so satisfying to the spirit, so defining of our character, than giving our all to a difficult task."
Many Mississippians watched with wonder, and a touch of disbelief, as Obama took the oath.
Willie Paige, a 72-year-old black man, watched the ceremony on television at Peaches, a soul food restaurant in Jackson. He said with a smile, "I tell you what -- I never thought I'd live to see it."
From the state Capitol to student dormitories to restaurants, Mississippians gathered to watch the inauguration.
State Sen. David Jordan of Greenwood said the inauguration of a black president "is above anyone's wildest dreams."
Obama made a brief campaign appearance at Peaches in June 2007, drawing only about three dozen spectators at a time he was still considered a long-shot candidate.
In Birmingham, thousands gathered in historic Boutwell Auditorium to view the inauguration on a huge video screen and give the hall the feel of a church revival.
In Montgomery about 3,000 people packed the basketball arena at Alabama State University. A huge cheer went up when Obama was sworn in.
Inauguration events also were being held in Selma and along the route taken by voting rights marchers in 1965.