2:57 p.m. ET
One of the classic challenges facing any new president is whether he can capitalize on the so-called honeymoon -- that period of 100 days, 180 days or however long Congress is willing to support the new president's agenda.
But with Democrats controlling both chambers, President Barack Obama's greatest task might be to sustain the energy level that millions of Americans demonstrated Tuesday.
The spirit of camaraderie linked to his inauguration had tinted Washington, D.C., since Friday. I heard an "Obama" chant break out in the 7-Eleven by my apartment building on Monday night. I saw tears in the crowd at the kick-off concert by the Lincoln Memorial Sunday. Tuesday on the National Mall, the gatherers even tried to hurry along the drawn-out formalities of the inauguration ceremony by shouting Obama's name louder and louder.
As they called for Obama to step on stage they jeered at outgoing President Bush and Dick Cheney. Some started singing: "Nah, nah, nah, nah. Hey, hey. Goodbyeeee." And they chanted for Obama some more.
But now that the ceremony's over, the reporters have largely cleared out of Capitol Hill and the tourists and Obama supporters are either lining up to watch the parade or starting their trips back home.
Obama, in his confident trademark delivery style, told more than 1 million on the Mall and millions more at home that his presidency would turn a page. After a campaign that drew in unprecedented crowds and dollars, he assured that while his administration would face tough challenges the energy of the Obama movement is real and lasting.
"Now, there are some who question the scale of our ambitions, who suggest that our system cannot tolerate too many big plans. Their memories are short. For they have forgotten what this country has already done," he said.
"What the cynics fail to understand is that the ground has shifted beneath them -- that the stale political arguments that have consumed us for so long no longer apply."
12:43 p.m. ET
Barack Obama, in his first moments as president, reaffirmed his goals of rebuilding the nation's image and promise.
The speech seemed to develop on the themes he struck in Berlin over the summer, and in Grant Park on Election Night.
"America is a friend of each nation and every man, woman and child who seeks a future of peace and dignity, and we are ready to lead once more," Obama declared. "We are the keepers of this legacy."
His speech seemed to pass by almost instantly. My picture- and note-taking might have sped up the clock. But in the end, it was about 20 minutes -- just what his aides had predicted.
Even so, hundreds of thousands of people have endured freezing temperatures and cramped spaces for 20 minutes. That's a statement in itself of how powerful and engrossing the setting in Washington is right now.
Even Obama acknowledged he was standing and speaking during a moment that would define a generation.
And the enthusiasm of the crowd has not waned. They cheered through Obama's speech and even threw back a call-and-response as the Rev. Joseph Lowery gave the benediction to close the ceremony. A number of spectators walked and glided across the frozen pond in front the Capitol building as people finally started to file out.
12:15 p.m. ET
The elation and energy and emotion in the crowd is brimming. Barack Obama has just taken the oath -- using a piece of history to make history by swearing on Abraham Lincoln's inaugural Bible.
The crowd erupted, waving signs and cheering as Obama stepped to the podium to deliver his address.
"On this day, we gather because we have chosen hope over fear," Obama declared. As expected he is talking about the tough challenges facing America, but he emphatically predicted: "Know this America, they will be met."
11:58 a.m. ET
Few in the crowd of thousands cheered for pastor Rick Warren when he walked on stage to give the invocation at Barack Obama's inauguration.
Warren's opposition to gay marriage has made him unpopular with many of Obama's supporters. But the crowd cheered all the same when in his prayer Warren addressed Obama's historic achievement as the nation's first African American president.
"We are so grateful to live in this land," Warren said, describing how a son of an African immigrant has risen to the highest office in the nation.
Warren referenced Jesus Christ only in terms of how he has influenced his life. He did speak at length of the historical significance of the day and of the common principles shared by Americans.
As he spoke, Obama and President Bush sat just a few feet from one another. They smiled at each other as they took their seats, just having arrived from the White House together. Obama defeated John McCain in large part by linking him to Bush. But with the transfer of power so close, maybe bygones are bygones
10:43 a.m. ET
The pomp and circumstance of the 56th presidential inauguration is underway. First the San Francisco Girls Chorus and Boy Chorus, then the crisp U.S. Marine Band played a few musical numbers.
The Marine Band continued to serenade as dignitaries were introduced in groups and filed into the VIP seating behind Barack Obamas podium.
The ceremony leading up to the swearing-in is actually so contained and formal it's easy to forget how many people are watching. From our vantage point, the performance and pageantry appears to take place for the dozens of ticketed guests in the front, who are quietly standing around in clusters or sitting down.
Celebrities are surely in the mix but so many in the front are wearing oversized fur coats and hats its hard to tell who's who.
A look to the left shows hundreds of thousands of spectators that were there this morning have not budged.
9:36 a.m. ET
The official Inauguration Day program hasn't begun but the dozens of reporters and cameramen on the Capitol riser are busy trying to cram in their live shots and interviews before the cutoff.
We have until 10:59 a.m., and then all reporters are required basically to stop talking until after the ceremony. Most are trying to offer a glimpse of what Barack Obama will discuss in his address -- a call to service and responsibility as well as a call for unity, perhaps in the same vein as his 2004 Democratic convention speech.
Media are stacked on about a half-dozen wooden planks, each with 20-30 or more people on them. Wires are tangled everywhere, reporters are losing cell and BlackBerry service. And most of us are just staying put where we are, since trying to leave the platform means tripping over tripods, people and cables on the way out.
The scene is the opposite of that several weeks back, when embedded producers and correspondents tagged along with Obama as he took his Hawaii vacation. There, reporters did live shots in sandals and swim trunks. Today, in freezing temperatures in Washington, D.C., anchors from the waist down are covered in blankets.
FOX News' Wendell Golder and Jim Angle, down on the first plank, both were enjoying the luxury of fuzzy blankets.
8:43 a.m. ET
The 200,000 Europeans who attended Barack Obama's Victory Column address during his overseas campaign tour will be dwarfed by the crowd in Washington, D.C., for Inauguration Day.
Ticket holders have started to file into their seats in front of the Capitol steps, but hundreds of thousands are already on the National Mall. Flashbulbs are firing from the mass of people standing arm-to-arm. Jumbo TV screens are sticking out of the Mall all the way back to the Washington Monument.
I've never been to the Olympics, but that is the only fair comparison I can draw. Except there's just one event -- the joint oath of office and the speech.
FOX Business Network's Peter Barnes is standing next to me on the cramped media platform outside the Capitol, running down some of the numbers: Nearly 7,000 tour buses, another 7,000 portable toilets and quite possibly the largest crowd ever assembled on the Mall.
The program doesn't start for more than an hour, and the area where Obama will speak is relatively empty. A handful of officials are walking up to the podium to inspect it, but the optics are all in place.
The West Front of the Capitol dome is draped in variations of the American flag. The music stands for the U.S. Marine Band are set up on the ground below. Semicircles of VIP seating fan out behind the podium.
Sen. Dianne Feinstein, D-Calif., the head of the Joint Congressional Committee on Inaugural Ceremonies, will kick things off here following a few musical selections. Until then, the media on the riser are just trying to keep their toes warm.
7:37 a.m. ET
The sun is rising over the U.S. Capitol steps, and inauguration spectators have already been filing into the city for hours. The National Mall is filled all the way back to the Washington Monument.
This, despite the fact that its frigid cold and the chances of snagging a decent vantage point of Barack Obama as he is sworn in are rail slim.
Right now, I'm sitting on about four square feet of space that I can call my own on the media riser directly to the left of the podium where the next president will speak.
Getting there was a struggle, but probably only half of what field reporters, guests and onlookers will endure once the crowds really start to arrive.
Crowd estimates have swung wildly, as guesstimators tried to figure the balance between people's desire to be there when Obama becomes the first black president and their aversion to cold and crowds. The former is winning.
Metro, Washington, D.C.'s public transit system, opened early at 4 a.m. ET, and by the time I boarded at 4:30 the trains on the red line going into the city were packed. Within 45 minutes of opening, Metro had off-loaded two trains on the line because they were overcrowded. Those who reached Union Station in one piece filed toward the gates, where they had to wait some more before they were allowed to enter the National Mall. Metro already set a record for Sunday ridership over the weekend, and I wouldn't be surprised if they set another today.