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(Charlie Archambault for USN&WR; National Archive/Newsmakers; Paul Richards/AFP/Getty Images)
Youth has always been a double-edged sword for America's presidents. It tends to inject the White House with fresh ideas and energy, but it can also lead to impetuousness and a disregard for the tried and true.
So far, Barack Obama has demonstrated both the positive and the negative sides of the equation. As the nation's fifth-youngest chief executive--he turned 48 on August 4--he is both innovative and vigorous, but at the same time he is unseasoned and perhaps too willing to experiment and take big risks.
Next: Theodore Roosevelt