SAN FRANCISCO/WASHINGTON - There will be no shortage of potent moments when Barack Obama stands on the steps on the West Front of the US Capitol Jan 20 to be sworn in as the 44th president of the US.

But few will match the poignancy of the fact that the first African-American president will be standing on a structure that was largely built by black slaves; that he will be sworn in using a Bible that was used by Abraham Lincoln, the martyred president who fought a Civil War to end slavery; or that he will be gazing down at the National Mall where Martin Luther King Jr inspired the civil-rights movement with his 1963 ‘I Have A Dream’ speech.

‘It closes the circle of history for African-Americans,’ said Jesse Holland, author of the recent book, ‘Black Men Built the Capitol’, which documented the roles of slave labour in building the physical symbols of US democracy.

‘The fact that you now have an African-American holding the highest office in the land - it doesn’t indicate that everything is perfect, but it’s a definite measure of success and improvement,’ he said in an interview with DPA.

Holland found that slave labour was involved in virtually every phase of the construction of the White House and the Capitol, from quarrying the Virginia limestone used in the imposing edifice of the Capitol to working on interior features.

He notes that the National Mall, which is now a vast, grassy park filled monuments, government offices and museums, was for many years the site of numerous slave markets.

‘Slavery was legal in the District of Columbia until President Abraham Lincoln abolished it in 1865,’ he said. ‘Most of the early occupants of the White House were slave owners, so it’s tremendously symbolic that Obama will hold his office inside a building that was constructed by slaves.’

Obama himself does not descend from a slave family, though his wife Michelle does. Obama’s black father was a Kenyan student in Hawaii, and genealogists have found that some ancestors on his white mother’s side were actually slave owners.

Nevertheless, on Jan 20 the colour of his skin will speak louder than his specific ancestry - symbolising the progress that African-Americans have made in a country that still enshrined legal segregation in some states less than 50 years ago.

Africans were mostly enslaved in America for some 250 years after they first started arriving in 1607. The Union victory in the US Civil War freed an estimated four million slaves by 1865, by which time they constituted some 10 percent of the entire country’s population.

But discrimination continued for more than 100 years as poll taxes, literacy tests and outright terrorism were all tools used to keep blacks from voting across the South. The one-time stronghold of slavery had a rigid system of apartheid, which subjected African- Americans to constant humiliation. Intimidation and lynchings were commonplace and mostly unprosecuted.

Despite the success of the civil rights movement, the black community continues to suffer from a lack of education and a paucity of economic opportunities. Blacks, who are 13 percent of the US population, suffer worse health and shorter life expectancy and account for 45 percent of the prison population.

The poverty rate among African-Americans is 24.5 percent, nearly twice the national rate and more than three times the poverty rate among non-Hispanic whites, according to US census figures.

Obama has acknowledged these difficulties, at the same time as he has challenged the black community to do more to fix its cultural problems and avoid wallowing in the stigma of victimhood. His ascension to power could provide a dramatic boost to those efforts.

‘The potency of the moment will travel far beyond the precincts of blackness,’ journalist Terence Samuel wrote on TheRoot.com, a website of black thought. ‘His success has been a repudiation of an ugly past and some absolution for our long and sinful racial history. That is an American story, and this is a different America.’