Barack Obama stood before a hushed nation today, raised his right hand and recited the 39-word oath to make history as the 44th president of the United States and the first African-American to assume the Oval Office.
Obama's historic moment -- and one that is a milestone for the nation -- was witnessed by an estimated 1.9 million throng on the National Mall, which erupted into cheers and a blizzard of American flags as he uttered the words "so help me God" at the conclusion of the oath. A military band launched into "Hail to the Chief" and tears streaked the faces of many in the delighted crowd.
That exuberance pervaded a day of pageantry starting with Obama's inaugural address and continuing through the parade in which hundreds of thousands waved, took pictures and called out to the president with unflagging enthusiasm.
When Obama twice emerged from his presidential limo with a big smile on his face, the cheers surged into a crescendo. The president was joined by his wife Michelle as they strolled a few blocks of Pennsylvania Avenue, waving to the screaming crowds on both sides of the avenue and at times holding hands.
Before taking center stage alone, Obama gave his predecessor, now former President George Bush, a final handshake as the 43rd president and his wife, Laura, boarded a chopper to make their way to their new home in Texas. The Obamas along with Vice President Joe Biden and his wife Jill waved as the chopper took the Bushes into retirement.
The one moment tinged with sadness occurred when Sen. Edward Kennedy, D-Mass, an instrumental supporter in Obama's election suffered a seizure and collapsed during a celebratory luncheon in Statuary Hall in the Capitol. Kennedy, 76, who was diagnosed with malignant brain cancer in May was taken to a hospital by ambulance.
In addition to Kennedy, Sen. Robert Byrd, 91, of West Virginia was also removed from the hall by wheelchair, apparently distraught over Kennedy's collapse. Kennedy was later reported to be in stable condition.
Obama entered the history books with his hand on a Bible that was held by his wife, Michelle, and was once used by the sixteenth president of the United States, Abraham Lincoln.
When taking the oath of office, Obama used his full name, Barack Hussein Obama, including his middle name that was rarely used during the campaign except by his enemies.
Obama's unflappable demeanor showed slight cracks when he failed to suppress a grin in the moments before his swearing in and then when he was briefly tripped up by Chief Justice John Roberts, who flubbed part of the oath he was administering.
The crowd, enduring a cold but sunny day, was thrilled by the changing of the guard and broke into chants of "Obama, Obama." But the 47-year-old president quickly turned serious.
He called the nation to an "era of responsibility" and told an America faced with an economic crisis and two wars, "Starting today, we must pick ourselves up, dust ourselves off, and begin again the work of remaking America."
Striking a more dour tone than those of his speeches on the campaign trail, Obama said the country faced a crisis of confidence as much as a crisis of the economy.
"Homes have been lost; jobs shed; businesses shuttered," he said. "Less measurable but no less profound is a sapping of confidence across our land -- a nagging fear that America's decline is inevitable, and that the next generation must lower its sights."
From enumerating America's problems he called on Americans to take action and not stand idly by, repeating a theme of Monday's day of national service.
"Our time of standing pat, of protecting narrow interests and putting off unpleasant decisions, that time has surely passed. Starting today, we must pick ourselves up, dust ourselves off, and begin again the work of remaking America," he said.
"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," Obama said. Taking responsibility, he said, is "the price and the promise of citizenship." To boost the economy, Obama pledged to implement the national infrastructure projects he has been promoting and pitching to Congress in recent weeks.
"Everywhere we look, there is work to be done," he said.
Addressing U.S. foreign policy and subtly repudiating President Bush's decision to go to war in Iraq, Obama said "power alone cannot protect us, nor does it entitle us do as we please."
The closest he came to acknowledging his status as the nation's first African American president was when he cited the country's "noble idea? the God-given promise that all are equal, all are free and all deserve a chance to pursue their full measure of happiness."
He noted that "a man whose father less than 60 years ago might not have been served at a local restaurant can now stand before you to take a most sacred oath."
The historical moment was deeply personal and moving for many Americans but struck a particularly deep chord with African-Americans.
"We brought in a new president who is capable and qualifed and happens to be African-American," said former Secretary of State Colin Powell. "I'm not ashamed to say, in fact I'm proud to say. I was tearing up just like everybody else."
Many of America's best-known celebrities attended the event. Actor Denzel Washington and former NBA player Magic Johnson had seats near the rostrum.
The legendary singer Aretha Franklin sang "My Country 'Tis of Thee" and was followed by a quartet that included Yo-Yo Ma and Itzhak Perlman who performed a composition composed by John Williams.
Following the speech, the Obamas went to the President's Room in the Capitol and signed three executive orders to maintain the continuity of government, his first official act as president.
Before the ceremonies at the Capitol, the Bushes greeted the Obamas at the White House. Michelle Obama hugged Laura Bush, and handed her a box wrapped in a red ribbon. The men shook hands, and the four of them turned and posed briefly for photos before heading inside.
They later emerged to ride together to the Capitol for Obama's rendezvous with history.
The Obamas began their day of public events by leaving Blair House for a service at St. John's Church in Lafayette Square, so-called the Church of Presidents where commanders in chief dating back to James Madison have knelt and bowed their heads before taking the oath of office.
The Obamas rode in the new presidential limo with the simple license plate number of "USA 1."
Obama and his wife sat in the center of the first row as the congregation stood and sang a hymn. At one point during the ceremony, Joel Hunter instructed those sitting near Obama to place their hands on his shoulders and head as a "spiritual means of giving grace."
The service's main speaker, Bishop T.D. Jakes, spoke of the many trials Obama will face, told Obama that "God goes with you" and then added that his 14-year-old son would probably offer Obama a different benediction.
"He probably would use Star Trek instead, and so I say, 'May the force be with you,'" Jakes said confusing "Star Trek" with "Star Wars."
The service was the first event of a day filled with traditions and significance, but those hallowed acts took on the added historic power -- and for many bolster the proceedings' sense of exhilaration -- as they are carried out for the first time in 220 years by an African-American.
More than a million people flocked to the National Mall to witness history.
They poured into the Mall viewing area throughout the night, smiling, waving and bundled up against the frigid overnight temperatures. Some even came chanting "Obama, Obama" and "Yes, we can."
The darkness glittered with the flash of thousands of cameras as attendees turned the long wait into an impromptu party.
The areas closest to the steps were packed well before sunrise, and by the time the sun came up the Mall was a sea of people.
Still they came, lined up for blocks as they patiently waited to get cleared by the massive security cordon, and subways from surrounding suburbs were jammed with people hoping to squeeze into the Mall party. By mid-morning, the National Parks Service stopped allowing people onto the Mall and redirected them to the Washington Monument grounds.
As the throngs gathered outside, Bush carried out one of his last acts and one of the oldest presidential traditions. He wrote a note to the incoming president and left it in the top drawer of the Oval Office desk. By tradition, the contents of those notes are never revealed.
And across the street in Blair House, Obama received the first of what will become a near daily exercise: his national security briefing. At this first briefing, the military aide who carries the briefcase with nuclear codes -- known as the "football" -- instructed Obama on the protocol surrounding it.
A long weekend of concerts and celebrations were prelude to today's inauguration.
Obama's history-making presidency comes at a historically critical time, as the United States faces the worst economic crisis since the Great Depression.
"An inauguration is a reminder that here in the United States, even after occasionally savage disagreements, we transfer power peacefully," said presidential historian and ABC News consultant Richard Norton Smith.
"Inaugurating the first African-American president is of enormous significance and adds an extra dimension and extra pride to the ceremonies, not just for African-Americans but for all Americans," he said.
Obama and Biden arrived in Washington, D.C., by train following a route that mirrored Abraham Lincoln's preinaugural trip in 1861.
Obama, who has struck a tone of confidence and cooperation during the transition, enters office with higher approval ratings than any incoming president since Ronald Reagan was inaugurated in 1981. Seventy-nine percent of Americans hold a favorable opinion of him.
The newly sworn in President Obama and the new first lady Michelle Obama are expected to attend seven official inaugural balls this evening. The first couple is expected to dance their first dance at the Neighborhood Ball to the Etta James classic "At Last" sung by Beyonce Knowles.