Millions of Americans will bring in a new era of United States' politics as they cast their votes in the most expensive presidential election in history.
As the £1.5 billion contest enters its final moments after almost two years of stump speeches, high-profile debates and political manoeuvres, Barack Obama leads his Republican rival John McCain by more than seven points in the latest average of national polls by RealClearPolitics.com.
As the Democratic nominee aims to become the first black president of the United States, his grandmother, who helped raise him and who played a significant role in forming his character and values, will be at the forefront of his mind after she died from cancer on Sunday night.
It is "one of the most important elections in the history of the country and the history of the world," Prof Allan Lichtman of the American University in Washington DC said.
The next president will have to face "perhaps the greatest financial crisis since the Great Depression", two wars in Iraq and Afghanistan, and "one of the gravest challenges in the history of mankind - catastrophic climate change".
Mr Lichtman also said the election will herald a "sea change" in America's relationship with the world as it moves from a primarily unilateral approach under George Bush to a multilateral one.
He said Mr Obama's nomination as the first African American nominee of any major US political party was a "great watershed for America" and not something that anyone would have expected 10 or even five years ago.
The 47-year-old Democrat was "the most significant breakthrough candidate in all American history", he said.
"He could do for race in America what John F Kennedy did for religion in America."
He went on: "If Obama wins and Obama governs as the president of all Americans, as I'm confident he will, he can do to the issue of race the same kind of transformations that John F Kennedy achieved for the issue of Catholicism in 1960."
