President Obama took office at the height of the worst downturn since the Great Depression. Following the collapse of Lehman Brothers in the fall of 2008, both weak and strong financial institutions faced panic-induced runs, and by last November, job losses rose to over half a million per month. Over the winter, any hope that the crisis might be limited to the United States was dashed as countries throughout the world began reporting breathtaking declines in GDP and trade.

The president's first task was to stop the economic...