Article published on the 2008-11-05 Latest update 2008-11-05 15:29 TU
More than 100,000 people piled into Grant Park stadium in Chicago to hear the President-elect give his acceptance speech.
Hundreds of thousands, maybe even a million, if Chicago mayor Richard Daley is to be believed, crammed the streets outside.
"If there is anyone out there who still doubts that America is a place where all things are possible, who still wonders if the dream of our founders is alive in our time, who still questions the power of our democracy, tonight is your answer," Obama said as he took the stage at midnight eastern time.
"Americans [have] sent a message to the world that we have never been a collection of red states and blue states. We are, and always will be, the United States of America," Obama said, adding that "change has come to America."
But he also struck a very serious and sombre tone, citing the financial crisis and ongoing wars in Iraq and Afghanistan as difficult challenges that lay ahead.
"This victory alone is not the change we seek, it is only the chance to make that change," Obama said.
Addressing those around the world watching his speech, Obama promised that "a new dawn of American leadership is at hand."
Outgoing President George W Bush was among the first to congratulate Obama by telephone.
"Mr President-elect, congratulations to you. What an awesome night for you, your family and your supporters ... I promise to make this a smooth transition. You are about to go on one of the great journeys of life. Congratulations and go enjoy yourself," Bush said according to White House officials.
"Your brilliant victory rewards a tireless commitment to serve the American people. It also crowns an exceptional campaign whose inspiration and exaltation have proved to the entire world the vitality of American democracy," French President Nicolas Sarkozy said in a letter to Obama.
"By choosing you, the American people have chosen change, openness and optimism," Sarkozy added.
British Prime Minister Gordon Brown praised Obama's "energising politics ... his progressive values and his vision for the future".
"This is a time for a renewed commitment between Europe and the United States of America," European Commission President José Manuel Barroso said in a statement. "We need to change the current crisis into a new opportunity. We need a new deal for a new world."
"In a new historical era, I look forward to... taking our bilateral relationship of constructive cooperation to a new level," China's President Hu Jintao wrote in a message to Obama.