Barack Hussein Obama today took the oath of office on the steps of the Capitol to become the country's 44th president, the culmination of three days of inaugural celebrations, three months of transition, two years of campaigning and -- many of today's speakers suggested -- more than 50 years of civil rights struggle.

Obama used the opportunity of his inaugural address to underscore the problems he will inherit, calling them "serious" and "many" and saying "they will not be met easily." As had been widely reported in the days leading up to the inauguration, the president's speech focused in large part on civic responsibility and called on citizens to "begin again the work of remaking America."

Obama has shown in the past he can do abstract and uplifting (his speech at the Iowa Jefferson-Jackson dinner), concrete and uplifting (his nomination acceptance speech in Denver) and concrete and pessimistic (his 2002 anti-war speech). This speech was abstract and pessimistic. Throughout, Obama framed the country's situation as perilous and his incoming administration as a crisis presidency, setting the stage rhetorically for what is likely to be major legislative action on the economy, energy and education.

But while he did not skirt the challenges facing his administration, Obama assured the American people that those challenges could be overcome by leaving behind petty partisanship in favor of a return to first principles. "The time has come to set aside childish things," he said. "The time has come to reaffirm our enduring spirit."

While Obama stayed away from anything too specific or wonky for an inaugural address, he did signal some of the areas where his administration seems poised to move in the coming months. He spoke of expanding prosperity beyond the wealthy and turning to alternative fuels, of increased funding for infrastructure and the necessity that the those in government "do our business in the light of day."

Several former presidential speechwriters took particular note of Obama's gestures towards other countries, especially the Muslim world. "By allowing his middle name, Hussein, to be used in the oath of office, and by his extension of this verbal olive branch, the new president seemed to be signaling to the Muslim world that their concerns will not be ignored by the new administration," former Clinton speechwriter Terry Edmonds told National Journal in an e-mail.

Reaching back past Abraham Lincoln, the president with whom he's most often compared, to close with a quote from George Washington, Obama recalled a time of crisis from the country's birth and the courage that overcame it. "With hope and virtue," he said, "let us brave once more the icy currents, and endure what storms may come."

More than a million people braved the icy currents of a Washington winter to pack the National Mall from the Capitol to the World War II Memorial, with scattered groups as far back as the Lincoln Memorial. Huge crowds clogged Metro stations and overloaded security checkpoints, even causing some ticketholders to be turned away. By 8 a.m. -- four hours before Obama took the oath of office -- many trash cans were already overflowing and large sections of the Mall were closed off.

There were scattered groups of those who had come with a cause to push -- Code Pink members protested the Iraq War near the press area, several Moroccan-Americans held signs asking that Obama visit their country -- but most came just to have been there. In the seating area directly in front of the Capitol, New York City Mayor Michael Bloomberg and actors Samuel L. Jackson and Dustin Hoffman mingled with the crowd of excited spectators.

The size and passion of the crowd speak to both the historic nature of Obama's inauguration and his success in maintaining the enthusiasm generated during the presidential campaign even as he's worked to contain expectations. The seemingly endless crowds of supporters -- who could be heard booing when Republican lawmakers were announced before the swearing-in ceremony -- could prove a valuable political asset once the new president begins pushing his agenda.

"I believe any objective measurement would show that the excitement and enthusiasm in Washington today, both before and after the inauguration, was even greater than it was 48 years ago for the Kennedy inauguration," Kennedy speechwriter Ted Sorensen wrote in an e-mail to National Journal.

For many in the audience, including the large contingent of former Tuskegee Airmen who were bused in to attend, the chance to see an African-American sworn in as president was worth pretty much any wait. Ngina Lythcott was arrested more than 25 times during the civil rights movement and, after participating in the 1963 march on Washington, thought she would never see a crowd as big again.

"The civil rights movement felt like I was fighting for my own rights," Lythcott said. "This movement has felt like a paradigm shift, that we are all moving to the next part of our collective lives."

Clarence B. Jones, a former speechwriter for Martin Luther King Jr., wrote in an e-mail to National Journal that he found it "inexplicable" that the president’s address contained no specific reference to King the day after the national holiday. But others were more forgiving.

"I think this speech will go down in history as one of the greatest inaugural speeches ever given," said Edmonds. "Not only because of its poetic language, brevity and Obama's customary confident and impassioned delivery, but also because today, America took a giant step in the perfection of our nation. As an African American, I was most touched by President Obama's acknowledgement of how far we have come."

The day took its toll on some of the event's better-known attendees, however. Two of the oldest-serving Democratic senators, Edward Kennedy of Massachusetts and Robert Byrd of West Virginia, were taken out of the post-inauguration luncheon by medical teams.

Amy Harder and Deron Lee contributed to this report.

Blogs