I call the first fact the Great Partisan Growth Divide. Simply put, the United States economy has grown faster, on average, under Democratic presidents than under Republicans.

Image Credit... David G. Klein

The stark contrast between the whiz-bang Clinton years and the dreary Bush years is familiar because it is so recent. But while it is extreme, it is not atypical. Data for the whole period from 1948 to 2007, during which Republicans occupied the White House for 34 years and Democrats for 26, show average annual growth of real gross national product of 1.64 percent per capita under Republican presidents versus 2.78 percent under Democrats.

That 1.14-point difference, if maintained for eight years, would yield 9.33 percent more income per person, which is a lot more than almost anyone can expect from a tax cut.

Such a large historical gap in economic performance between the two parties is rather surprising, because presidents have limited leverage over the nation’s economy. Most economists will tell you that Federal Reserve policy and oil prices, to name just two influences, are far more powerful than fiscal policy. Furthermore, as those mutual fund prospectuses constantly warn us, past results are no guarantee of future performance. But statistical regularities, like facts, are stubborn things. You bet against them at your peril.

The second big historical fact, which might be called the Great Partisan Inequality Divide, is the focus of Professor Bartels’s work.