Barack Obama made history on January 20, becoming the first African American President of the United States. He was inaugurated in front of an estimated 1.8 million people on the National Mall in Washington, D.C. Obama's presidency was marked by several significant events, including the passage of the Affordable Care Act, the killing of Osama bin Laden, and the signing of the Paris Climate Agreement. Despite facing numerous challenges, Obama's presidency is widely regarded as a transformative period in American history.