I'm not sure Obama has turned the economic tide. Unemployment is still high, we're still losing manufacturing jobs to China and other parts of the world and the stimulus spending under Obama's administration has been largely a failure. I call it a failure because the point of stimulus spending is to generate enough jobs to boost the tax base so that the government recovers the money it spent in an attempt to strengthen the economy. That didn't really happen.
On the other hand, I'm one of those rascals that maintains that a president can do very little to help an economy other than letting free enterprise thrive. In the case of the Great Depression, World War II was the single event that truly pulled the U.S. out of its dark economic times. Americans were put back to work to help with the war effort and, following the war, the battered economies of Europe were recovering and in need of the manufactured goods America was producing like crazy.
Please bear in mind I'm not out to bash either Roosevelt or Obama. The point is that a president has limited power to improve the economy. Still, one of the things a president can do is charge tariffs against any goods made outside the U.S. that are to be sold in American markets. That's an anti-free trade move, but I'd support it in a heartbeat.