Should-Read: Dodge Cahan and Niklas Potrafke: The Democratic-Republican Presidential Growth Gap and the Partisan Balance of the State Governments: “Higher economic growth was generated during Democratic presidencies compared to Republican presidencies… http://econpapers.repec.org/paper/cesceswps/_5f6517.htm

…Blinder and Watson (2016) explain that the Democratic-Republican presidential growth gap (D-R growth gap) can hardly be attributed to the policies under Democratic presidents, but Democratic presidents–at least partly–just had good luck, although a substantial gap remains unexplained. A natural place to look for an explanation is the partisan balance at the state level. We show that pronounced national GDP growth was generated when a larger share of US states had Democratic governors and unified Democratic state governments. However, this fact does not explain the D-R growth gap. To the contrary, given the tendency of electoral support at the state level to swing away from the party of the incumbent president, this works against the D-R growth gap. In fact, the D-R presidential growth gap at the national level might have been even larger were it not for the mitigating dynamics of state politics (by about 0.3-0.6 percentage points). These results suggest that the D-R growth gap is an even bigger puzzle than Blinder and Watson’s findings would suggest…