Some numbers, such as the low saving rate and the colossal current-account deficit, suggest that the economy's course is unsustainable.

ECONOMIST: What will guide the new boss of America's Federal Reserve?

Since the current-account balance equals the net saving of the private and public sectors, a budget deficit boosts the external deficit.

ECONOMIST: America's current-account deficit

Instead, his legacy will linger in the shape of the biggest economic imbalances in American history: a negative household saving rate and a record current-account deficit (see chart 1).

ECONOMIST: Alan Greenspan