"America, this is our moment. This is our time. Our time to turn the page on the policies of the past," Obama told more than 19,000 screaming supporters in St Paul, Minnesota, as thousands more watched on screens outside.
Speaking with the eloquence and vision that has given him the following of a rock star, Obama promised history would show that "this was the moment, this was the time, when we came together to remake this great nation so that it may always reflect our very best selves, and our highest ideals."
Ricardo Johnson, 42, was brought to tears by Obama's victory.
The African-American father-of-four waited for more than three hours to land front row seats near the stage, and described his emotion at being there.
"It means everything. To have my children here and watching this man speaking for himself, thinking for himself, and leading this nation and my children's future in a new direction, it means everything," he said.
Johnson, a small business owner, wiped a tear from his cheek as his 12-year-old son jumped up, shaking his fist in the air to a song accompanying a video of Obama.
The boy wore a visor cap announcing "Obama for President '08" and on his back, a t-shirt with Obama's face and the slogan "sharing the dream."
For Sudanese immigrant Sulafa Simsaa, the night was an affirmation of the promise of the United States.
"It truly reflects what this country is based on -- which is that it is a land of equal opportunity for everybody," the 23-year-old said.
"Having a black president proves the point that with enough determination, anybody can make it."
Obama claimed his hard-fought victory over Hillary Clinton in the same arena where rival John McCain will be anointed the Republican presidential nominee during the party's September convention.
"It's overwhelming," Democratic senator Amy Klobuchar of Minnesota told AFP as she shook hands in the crowd.
"They're going to yell so loud that when the Republicans come here in September they're still going to be hearing the echoes."
The noise from the crowd was indeed deafening.
Some 19,000 screaming supporters waved US flags and blue signs calling for "change we can believe in" and chanted "yes we can!" as Obama mounted the stage with his wife, Michelle, to the sound of U2's "It's a Beautiful Day."
Among them was Nancy Edwards, a 64-year-old grandmother who danced in an aisle in a black t-shirt she had printed up with bold white letters stating "white woman over 50 for Obama."
"This is the highlight of my entire life," the beaming Edwards said.
"This is the tops. This is everything. This man has more integrity than anyone I've ever known and I haven't even met him yet. I trust him."