Black, white or no matter what this is a moment in history for all people of the United States.

The 47-year-old Barack Hussein Obama was just sworn into the office by Chief Justice John Roberts as the 44th president of the United States after Joe Biden sworn in as vice president minutes earlier.

With a hand on Abraham Lincoln's inaugural bible used to swear in 1861, and before a crowd stretching across the National Mall toward where Martin Luther King Jr. spoke of his dream of racial equality Obama recited the 35-word oath of office.

Obama inherits one of the worst economic crises endured by this nation and ongoing terror threats to interests at home and abroad.

Today I say to you that the challenges we face are real. They are serious and they are many. They will not be met easily or in a short span of time. But know this, America... they will be met, Obama said.

Obama's show of unity has been extraordinary. His solid alignment with a great Republican President, Abraham Lincoln has shown his desire to have this wall of party differences broken down.

On this day, we gather because we have chosen hope over fear, unity of purpose over conflict and discord. On this day, we come to proclaim an end to the petty grievances and false promises, the recriminations and worn out dogmas, that for far too long have strangled our politics he said.

After the swearing in and his inaugural address, Obama will see off outgoing President.

The new president had kisses for his wife, Michelle, and his school-age daughters, Malia and Sasha, then he turned to the crowds stretching away into the distance on a cold, windy day.

Hundreds of thousands of people erupted in roars of approval on the broad National Mall grounds as they watched. Obama, Obama, the crowd cheered.

In the days leading up to today's inauguration, Obama has signaled that he is prepared to dive into the nation's most pressing problems, particularly its moribund economy.