The greatest pilgrimage in modern American history is about to begin. Thousands of buses have been chartered, many from the Deep South. Camp sites have been booked because hotel rooms even 150 miles away have been sold out for months. Trains and planes en route for Washington are preparing for one of their busiest 48 hours, all courtesy of one historic moment ten days from now.

Just before noon on January 20 Barack Hussein Obama will place his left hand on the cover of the Lincoln Bible to be sworn in as America’s 44th – and first black – President, an extraordinary moment of personal triumph that will be watched by the largest gathering of Americans in Washington’s history.

He will seek to invoke Abraham Lincoln, on a day he inherits the worst economy since Franklin D Roosevelt took office. Yet the sheer power of that moment – the sight of the country’s first black President being sworn in under the white-marbled splendour of the US Capitol – is the sole reason why so many African-Americans are beginning their pilgrimage to Washington for Inauguration Day.

The Secret Service and police concede that they simply do not know the size of the crowd that will assemble to witness this piece of history but everyone is agreed that it will far exceed the 1.2 million who mobbed Lyndon B Johnson’s 1965 inauguration, the only other moment in modern times when African-Americans descended on Washington enthused and excited by an incoming President, months after he had passed the Civil Rights Act.

Mr Obama’s ceremony will more than anything else be testament to a moment that many never believed they would see even after Johnson’s efforts 45 years ago.

The American Bus Association has told officials in Washington to expect at least 10,000 tour coaches. The sheer scale of the security and logistical challenges facing the city are unprecedented. For the first time the entire two-mile length of the National Mall will be open to the public for an inauguration, from the US Capitol down to the Lincoln Memorial. The Secret Service now believe the crowd will be between two and three million.

In another first, ten giant screens will sit along the Mall, allowing the throngs positioned too far from the Capitol to see the swearing-in to watch it from where they stand.

Mr Obama, having fled from his middle name Hussein during his presidential campaign, will use it in his inauguration, something that is not required. Neither Ronald Reagan nor Jimmy Carter employed their full names during their inaugurations.

A quarter of a million people, some of who paid heavily for the privilege, have coveted tickets that seats them in front of the US Capitol. A string of Hollywood celebrities, including Halle Berry, Sharon Stone, Steven Spielberg and Jamie Foxx gave the maximum $50,000 (£33,000) donation to Mr Obama’s inaugural committee, which pays for much of the day’s events. In return they get access to candlelight dinners with appearances by the Obamas, entrance to an official ball – and seats close enough to see the swearing-in ceremony.

One man who did not have to pay, George Bush, will leave Washington as soon as the ceremony is over, driven in a motorcade to Andrews Air Force Base for a flight home to Texas, his presidency over. “I will have a front-row seat in a moment in American history,” he said last month.

Also sitting beneath the Capitol will be Mr Obama’s Kenyan grandmother, Sarah Obama, and his half-sister, Maya Soetoro-Ng. They will not only see him sworn in but will also be entertained at the ceremony by Aretha Franklin and Yo-Yo Ma.

That night there will be ten official inaugural balls – including a new Neighbourhood Ball for ordinary Americans – and dozens of unofficial ones, one of which will feature Sting and Elvis Costello.

Mr Obama will be sworn in on the 1,280-page, 1853 burgundy velvet Bible used by Lincoln during his 1861 inauguration. The President-elect has decreed that the theme of the day is “Renewing America’s Promise”, a phrase taken from Lincoln’s 1863 Gettysburg Address.

The Secret Service has, in effect, ordered central Washington to be sealed off. No cars will be allowed to cross over the Potomac River from Virginia. In what are expected to be brutal conditions – the average temperature in Washington on January 20 is just above freezing – those entering the Mall will not be allowed backpacks, baby strollers, lunchbags or umbrellas.

More than 5,000 portable toilets will line the stretch. Organisers admit that they are in unchartered territory and cannot predict what might befall the city with such a large crowd.

The city’s subway will deploy 850 rail cars capable of carrying 120,000 people every hour from 4am to 7pm.

More than 4,000 city police officers will be deployed, along with another 4,000 from 96 other law-enforcement agencies. About 7,500 active-duty US military personnel and about 4,000 National Guard will also be on duty. The day will not be without controversy. Gay rights groups have been outraged by Mr Obama’s choice of the evangelical pastor Rick Warren to deliver the invocation, because he has compared homosexuality with incest. The President-elect has defended the choice, saying: “What we have to do is create an atmosphere where we can disagree without being disagreeable”.

The official countdown to the inauguration begins on January 17 when Mr Obama boards a train in Philadelphia for Washington, picking up Vice-President-elect Joe Biden. They will then attend a “welcome event” at the Lincoln Memorial. All eyes are on the weathermen. A big freeze would certainly rain on Mr Obama’s parade.

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