Source: The New York Times - Link
A president has only limited control over the economy. And yet there has been a stark pattern in the United States for nearly a century. The economy has grown significantly faster under Democratic presidents than Republican ones.
It’s true about almost any major indicator: gross domestic product, employment, incomes, productivity, even stock prices. It’s true if you examine only the precise period when a president is in office, or instead assume that a president’s policies affect the economy only after a lag and don’t start his economic clock until months after he takes office. The gap “holds almost regardless of how you define success,” two economics professors at Princeton, Alan Blinder and Mark Watson, write. They describe it as “startlingly large.”
I’ve always heard this was the case. Some interesting data here.