Barack Obama will make history on January 20 when he is inaugurated as the 44th president of the United States and becomes the first African-American to hold the job.
In the wake of his election victory in November, Mr. Obama promised to follow through on a campaign pledge he made when he began his presidential quest nearly two years ago.
"It has been a long time coming, but tonight, because of what we did on this day, in this election, at this defining moment, change has come to America," he said.
But the president-elect has also made it clear that his first priority will be a massive government spending plan designed to jolt the weak U.S. economy back to life.
"A world that depends on the strength of our economy is now watching and waiting for America to lead once more," added Mr. Obama. "And that is what we will do."
Mr. Obama comes into office at a time when the country faces great challenges at home and abroad.
The president-elect is expected to use his Inaugural Address to reassure Americans about the country's economic future, much as President Franklin Roosevelt did during his first inaugural in 1933 in the Great Depression.
"So first of all, let me assert my firm belief that the only thing we have to fear is fear itself," said Roosevelt.
Given his already legendary oratorical skills, Obama supporters also expect the president-elect to be inspirational in his Inaugural Address, perhaps along the lines of President John Kennedy's famous call to public service at his inaugural in 1961.
"And so my fellow Americans, ask not what your country can do for you. Ask what you can do for your country," said Mr. Kennedy.
Presidential inaugurations have long been seen by the public as one of the enduring symbols of American democracy.
"We do not have that many rituals in American politics. And the inauguration ritual is very important because it marks the peaceful transfer of power from one administration to another, and in this case from one party to another," said Allan Lichtman, a presidential historian at the American University in Washington.
Past presidential inaugurals have often been seen as markers of change and political shifts in the United States.
In 1981, President Ronald Reagan used his Inaugural Address to underscore his basic philosophy of relying less on the government and more on private enterprise and the power of individuals.
"In this present crisis, government is not the solution to our problem. Government is the problem," said Mr. Reagan.
Like President Reagan, Mr. Obama faces the daunting task of turning around the U.S. economy as his number-one priority.
Brookings Institution scholar Stephen Hess says that while Mr. Obama does face great challenges, solving those problems also presents the new president with opportunities.
"He has this most remarkable agenda and that in itself is the opportunity for greatness. You look at the history of the United States, and when we talk about great presidents, think back in retrospect, they were all great presidents at very important moments," he said.
Mr. Obama is already headed for the history books because of his status as the first African-American president.
Allan Lichtman says that fact will not be forgotten in the celebrations surrounding his inauguration.
"The White House itself was built by slaves, and now we have an African-American in office far earlier than most experts would have expected. Barack Obama is a true phenomenon in American politics," he said. "And he seems to have transcended race. He campaigned as the candidate of all Americans, not the candidate of black America."
The impact of Mr. Obama's inauguration will also extend far beyond the borders of the United States.
Expert Stephen Hess says the unprecedented international interest in this year's presidential campaign should continue into the early months of Mr. Obama's presidency.
"And he has the roots in the Pacific, not only in our Hawaii, but in Indonesia. He has got the African roots with his father," said Hess. "All of the world feels they have some connection to this new president of the United States.
Mr. Obama begins his presidency with a measure of public good will. Recent polls show public approval for his handling of the presidential transition and suggest that many Americans, at least early on, have confidence in his ability to lead and unify the country.