They did it. They really did it. So often crudely caricatured by others, the American people yesterday stood in the eye of history and made an emphatic choice for change for themselves and the world. Though bombarded by a blizzard of last-minute negative advertising that should shame the Republican party, American voters held their nerve and elected Barack Obama as their new president to succeed George Bush. Elected him, what is more, by a clearer majority than one of those bitter narrow margins that marked the last two elections.

Having snatched defeat from the jaws of victory in 2000 and 2004 it felt at times fated that the Democrats would somehow complete a hat-trick of failures on election day 2008. Instead, fuelled by unprecedented financial support, the key things went right for them yesterday, from the moment just after midnight when Dixville Notch voted 15 to six for Mr Obama (the first time the early-voting New Hampshire hamlet had gone for a Democrat in 40 years), through to the early Obama success last night in the prized swing state of Pennsylvania and on into the battleground areas of middle America.

In the last two presidential elections, the American people divided down the middle, producing a both a geographical and a demographic divide that seemed increasingly set in stone. Blue Democratic America consisted of the west and the east coasts plus the upper Midwest. Red Republican America covered the swaths in between. Women, minorities, the poor and the highly educated voted Democratic. Men, white people, the rich and the religious delivered for the Republicans. In the mind of Mr Bush's strategist Karl Rove this division was the template of 21st century American politics, a base for a conservative counter-attack against 20th-century liberalism.

Rove's America was not just turned on its head yesterday. It was broken up and recast in a very different mould. One of Mr Obama's many achievements has been his refusal to accept the permanence of the blue-red divide. He has reached out across the divide to states and voters that the embattled Democratic party of the Reagan-Bush years had forgotten about, places like the South and the Rockies, voters like farmers and small business people.

With the Democrats powerfully consolidating their position in both houses of Congress yesterday, the shift was consolidated at state and district level. This marks the end of the conservative ascendancy of the past 30 years. Whether it now marks a new, sustained era of American liberalism of the sort which followed the election of 1932 must remain to be seen. What is not open to doubt is that Mr Obama's win is a milestone in America's racial and cultural evolution. It is 45 years since Martin Luther King, in the greatest of all late-20th century American speeches looked forward to the day when his children would not be judged by the colour of their skin but by the content of their character. Almost unbelievably, that dream has now become a reality in the shape of America's first African-American leader and its first black first family. It is a day many thought they would never see. It is hard to know whether to weep or shout for joy now that it has arrived - probably both - but it is a lesson to the world.

Mr Obama will take office in January amid massive unrealisable expectations and facing a daunting list of problems - the wars in Iraq and Afghanistan, the broken healthcare system, the spiralling federal budget and America's profligate energy regime all prominent among them. Eclipsing them all, as Mr Obama has made clear in recent days, is the challenge of rebuilding the economy and the banking system. These, though, are issues for another day. Today is for celebration, for happiness and for reflected human glory. Savour those words: President Barack Obama, America's hope and, in no small way, ours too.