Democratic Senator Barack Obama has been elected the first black president of the United States, according to projected results.
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.
As the US presidential election came to a climax supporters of the two main candidates began to react to news of the results.
Democratic Senator Barack Obama won two key battleground states early on, giving him a strong lead in the presidential race.
Thousands came to Grant Park, Chicago, where Mr Obama addressed an election-night rally.
The mood was upbeat as the results were called. A million people were expected to attend the Grant Park event.
A subdued atmosphere marked the election-night rally of Republican John McCain as it became clear that Mr Obama was surging ahead in the count.
Mr McCain is projected to have won: Kentucky, South Carolina, Oklahoma, Tennessee, Arkansas, Alabama, Kansas, North Dakota, Wyoming, Georgia, Louisiana, West Virginia, Texas.
Mr Obama is projected to have seized states including Ohio, New Mexico and Iowa - all Republican wins in 2004.
Many Americans said they felt they had voted in a historic election.