Democratic Senator Barack Obama has been elected the first black president of the United States.
Several states reported very high turnout. It was predicted 130 million Americans, or more, would vote - more than for any election since 1960.
His rival John McCain accepted defeat, saying "I deeply admire and commend" Mr Obama. He called on his supporters to lend the next president their goodwill.
Mr Obama captured the key battleground states of Pennsylvania and Ohio, before breaking through the winning threshold of 270 electoral college votes at 0400 GMT
Thousands came to Grant Park, Chicago, where Mr Obama addressed an election-night rally.
Obama said: "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 added: "The road ahead will be long. Our climb will be steep. But America - I have never been more hopeful than I am tonight that we will get there."
The mood was upbeat as the results were called. A million people were expected to attend the Grant Park event.
Mr Obama appeared with his family, and his running mate Joe Biden, before the huge crowd.
Many Americans said they felt they were voting in a historic election, not least because of the possibility of choosing the first African-American president.
Some, including the Rev Jesse Jackson, were overwhelmed by the momentous occasion.
Democratic supporters celebrate across the country, here in Times Square, New York.
Around the globe supporters of Barack Obama celebrate as news filters through.
Residents of Kogello, the village in Kenya where Obama's father was born, dance during the night.
In Paris celebrations spill onto the streets.
For the Republicans the night ended in defeat. Flanked by his wife Cindy and his running mate Sarah Palin, McCain addressed his supporters in Phoenix.
McCain said: "We fought as hard as we could. And though we fell short, the failure is mine, not yours."
McCain praised his running mate, Sarah Palin. He said she is, "one of the best campaigners I have ever seen, and an impressive new voice in our party for reform."
Republican President George Bush called Obama to congratulate him on his victory, he said: "You are about to go on one of the great journeys of life. Congratulations and go enjoy yourself."
But the night belonged to Barack Obama who admitted: "The road ahead will be long. Our climb will be steep. But America - I have never been more hopeful than I am tonight that we will get there."