WASHINGTON (AFP) – Excitement is swelling across the United States and the world as Barack Obama prepares to be sworn in Tuesday as the nation's first black president witnessed by the largest inauguration crowd in history.
"This is a moment of hope and pride for our whole nation. And I join all Americans in offering best wishes to president-elect Obama, his wife Michelle, and their two beautiful girls."
But with some two million people expected to attend the event along with a veritable "who's who" of Hollywood stars, sporting heros and political heavyweights, the tightest security operation ever mounted in the nation's capital swung into action at the weekend.
Nothing on this scale has been seen since the 1965 inauguration of John F. Kennedy's successor Lyndon Johnson, attended by 1.2 million people.
And anxious security officials have been poring over plans for months. More than 12,500 active troops and military reservists and thousands of police are being drafted in as a security blanket descends on the city.
"I think we all have to be concerned about a chemical, biological, radiological potential attack," Major General Richard Rowe, head of the Armed Forces Inaugural Committee, said last week.
Some nine square kilometers, a huge swathe of the downtown area encompassing the White House, the National Mall and the Washington Monument, is being locked down from Monday afternoon until just after dawn on Wednesday, with traffic restrictions in place already from Saturday.
There will only be 13 entry points into the giant pedestrian area, with officials expecting long queues. And visitors are banned from bringing any backpacks, strollers, water bottles, or fold-up seats.
Despite the fervor to be among those witnessing history, officials and even Obama's transition team are warning would-be spectators to think seriously about attending, with the young, old and infirm urged to stay away.
"Unprecedented numbers of Americans are planning to join us in Washington," said Obama said in a statement.
"That will mean long lines, a tough time getting around, and most of all, a lot of walking on what could be a very cold winter day."
A wave of Arctic cold which has swept over Washington is set to stay in place, possibly bringing some snow on Sunday and Monday, and with temperatures only reaching 30 degrees Fahrenheit (one degree Celsius) on Tuesday.
Obama has encouraged people to take part via the Internet, or by watching television, or by joining one of several events leading up to the inauguration which kicked off Saturday with his train ride from Pennsylvania to Washington.
On Sunday, tens of thousands are due to surround the Lincoln memorial for a free concert with such stars as Bruce Springsteen, Bono, Beyonce and Mary J. Blige, with the incoming president to take a starring role.
But the spotlight will be on Tuesday when Obama and vice president Joe Biden will take the oath of office towards midday on the steps of Capitol Hill. Obama will swear on the bible which once belonged to his hero, assassinated president Abraham Lincoln.
There will be a song from Queen of Soul, Aretha Franklin, as well as performances by Yo-Yo Ma, after the incantation to be given by controversial pastor Rick Warren.
Ten huge video screens and 100 loud speakers are being erected for the crowds. Afterwards Bush will depart for his ranch in Texas, and Obama will host a luncheon in the Capitol building.
Then a parade will march down Pennsylvania Avenue to the White House where Obama and his family will take up residence.
The festivities will continue long into the night as Washington rocks around the clock with a flurry of inaugural balls. Obama is hosting 10 official balls, but some of the unofficial balls may well be the place to be seen.
The first ball Obama and the new first lady will attend has been dubbed "The Neighborhood Ball" offering free tickets to residents in a break with past parties which have usually only catered to a powerful, wealthy elite.
Fashionistas are also eagerly waiting to see what Michelle Obama will wear.
"I'm sure she won't have an over-the-top gown studded with diamonds and rubies," said etiquette expert Letitia Baldrige, former social secretary to first lady Jackie Kennedy. "It will be something suitably quiet for the times."
And in another break with tradition on Wednesday, after a prayer service at the Washington Cathedral, the Obamas will throw open the doors of their new residence inviting people to take part in an Open House on Obama's first full day at work.