Chicago — It was a carnival mood last night at Grant Park in the middle of American Democratic candidate Baracks Obama's home city of Chicago.

Tens of thousands of supporters keeping a night vigil as results were beamed from across the country broke into screams of joy shortly after 10.00pm (7.00am Wednesday EAT) when it became clear that Mr Obama, the son of a Kenyan, had taken an unassailable lead in the electoral college count to become the first African-American president of the United States.

Shortly afterwards his Republican Party rival John McCain gave a graceful concession speech televised live from Phoenix City in his home state of Arizona, and Chicago went into a giant party sure to last throughout the night.

The crowds in Chicago had started gathering had started gathering at Grant Park in the early evening, and by 7.30pm (4.30 EAT) as Democratic Party candidate Obama started building up a seemingly impregnable lead of 174 electoral college votes to 64 for Republican rival John McCain, the city was ready to party.

A presidential candidate mist win a simple majority, 270 out of 538 Electoral College votes, to win the presidency.

Against a backdrop of the well-lit Chicago skyline, excited Obama supporters watched on giant screens as election results and projections from TV networks were beamed out.

The biggest cheers were reserved for announcements of victories in the hard-fought battleground states such as Ohio, Virginia, Iowa, Pennsylvania and Florida that throughout the last weeks of the campaign had remained too close to call and were set to determine the outcome. On the other side of the country in Phoenix, a muted and anxious McCain party was entertained by country music star Hank Williams entertained an anxious crowd that in no way matched the numbers, upbeat mood and global media interest in Chicago.

By 8.45pm when Mr Obama went past the 200 electoral vote mark with Mr McCain still under 100, the crowd grew at Grant Park grew even more ecstatic as it became clear he was headed for a resounding victory, especially because some of his key bastions on the west coast, including California with over 50 electoral votes, were still voting.

By then even the TV pundits were becoming unanimous that it would take a major miracle for Mr McCain to claw back his way into contention.

Just a few hours later when one of the remaining battleground states, Florida, went to Obama with the results from the western states still awaited, it was all over and historic victory was confirmed.

At exactly 11pm the new president-elect gave his acceptance speech, a sombre affair that celebrated a great achievement but also cautioned that the victory was not the end but the beginning of a long journey ahead.

Magnanimous in victory, Mr Obama was effusive in praise for his vanquished rival, lauding Mr McCain as a great, selfless and brave leader who had endured sacrifices few can imagine.

Mr Obama said his victory showed that all things are possible in America, but cautioned as even as the celebrations begin, all must remember that they are just starting on major challenges that include the financial sector crisis, simultaneous wars in Iraq and Afghanistan, the energy crunch schools and healthcare systems to repair.

His speech was interrupted by chants of his campaign slogan "yes we can," with some in the crowd yelling themselves hoarse while others stood still in stunned silence, tears streaming from their eyes as they savoured the historic moment.

"What began 21 months ago does not end on this solemn night", Mr Obama intoned, this victory today is not the change we seek, it is just the beginning".

Ahead lay major challenges that call for sacrifice, patriotism and hard work.