January 20, 2009: Barack Obama takes office as president of the US.

Barack Obama takes the oath of office administered by Chief Justice John Roberts Jr. on January 20, 2009. (Credit: Cecilio Ricardo / public domain)

Barack Obama takes the oath of office administered by Chief Justice John Roberts Jr. on January 20, 2009. (Credit: Cecilio Ricardo / public domain)

He had been elected on November 6, 2008. He will win reelection in 2012.