January 21, 2009: Clinton is sworn in as secretary of state.

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Hillary Clinton being sworn in as secretary of state, with Bill Clinton assisting, administered by Associate Judge Kathryn Oberly. (Credit: US Department of State)

She resigns as senator from New York at the same time. She was confirmed by the Senate earlier the same day.

She will serve for all of President Obama’s first term, until February 2013. (The Washington Post, 3/10/2015)