The crowd is expected to reach 600,000 on the National Mall and in front of the Capitol for the country's 57th Presidential Inauguration.
Far less than the estimated 1.8 million who gathered to watch the country inaugurate its first African American President in 2009.
During his 2009 Inaugural Address, President Obama spoke of a country in crisis as two wars were being waged and the nation's economy was in a free fall.
Michael Shear of the New York Times writes about the backdrop for today's Inauguration:
As he delivers his second Inaugural Address, Mr. Obama is presiding over an economy that has improved and warfare that has receded. But the world remains a dangerous place, the economy is still fragile, and many of the gauzy promises of action and progress from his first address have given way to the cold realities of politics and compromise and bitter gridlock.
You can watch today's festivities and Mr. Obama's address here live:
(OBAMA HAS DELIVERED HIS INAUGURAL ADDRESS. YOU CAN READ IT HERE)