And so Obama came before his supporters for the first time as president-elect late on Tuesday night sandwiched between two sheets of bulletproof glass.

You wouldn't have seen these shields on television - they were to the left and right of the camera's field of vision, to the left and right of Barack Obama like giant transparent bookends, protecting him from the public throng on either side.

In front of him were the tiered ranks of the world's television cameras; it was to them that he addressed his remarks, and it was only to them that he appeared free and unencumbered in his surroundings; to the rest of the crowd, he must have looked like a precious specimen in a case.

But it was a hell of a night to be in Grant Park, right in the middle of downtown Chicago and its nest of skyscrapers.

All day, Obama's home city had been edgy in the unfamiliar November heat.

For every local filled with optimism about the night's doings, there was another one who would darkly predict disaster.

So when the big screens began to carry news of Obama's steady progress through the American electoral map, the accompanying roars sounded mostly like triumph, but a bit like relief.

Every time a mighty Republican redwood was felled, a wall of sound issued from the throat of the crowd; Ohio, North Carolina, Iowa. When Virginia succumbed, Grant Park was alive with waving arms, and the din was extraordinary.

They were quiet - eventually - when John McCain appeared to make his concession speech.

It was a good speech, full of grace and dignity.

And Obama himself did not disappoint, with a speech that began as an appeal to America and the globe but then narrowed to the life of a single woman - Ann Nixon Cooper, a 106-year-old who might have lived out her days more or less unremarked had Obama not met her in Atlanta.

"And this year, in this election, she touched her finger to a screen, and cast her vote, because after 106 years in America, through the best of times and the darkest of hours, she knows how America can change."