Barack Obama took power as the first black US president on Tuesday and quickly turned the page on the Bush years, urging Americans to rally to end the worst economic crisis in generations and repair the US image abroad.
"Starting today, we must pick ourselves up, dust ourselves off, and begin again the work of remaking America," Obama said, addressing an exuberant sea of people in an inaugural speech that was optimistic but realistic about the challenges ahead.
He pledged bold and swift action to bring new life to the US economy and declared to millions watching abroad: "We are ready to lead once more."
Underscoring the tough road ahead, Wall Street ushered in the new presidency with a record Inauguration Day slide amid signs the global banking crisis was far from over.
Hundreds of thousands of people erupted in cheers on Washington's National Mall grounds as they watched Obama stand with one hand raised, one hand on a Bible used to swear in Abraham Lincoln in 1861, and repeat the brief oath to become the 44th US president.
Beaming, the new president kissed his wife, Michelle, and his school-age daughters, Malia and Sasha. Then he turned to the crowds stretching into the distance on a cold, wintry day.
"Obama, Obama," the crowd cheered.
Obama, a Democrat, succeeded Republican George W. Bush, who served two terms and left office having plumbed record lows in approval ratings and leaving a legacy of two wars and an economy in recession.
Obama offered a sharp break from Bush, emphasizing the need for sacrifice and pledging to restore U.S. global standing, responsibly end the war in Iraq, and focus less on the size of government and more on whether it works.