The NYT’s David Leonhardt published an article entitled “Blue vs red economic records” on February 2, 2021. It was labelled as an opinion, but the amount of data presented made it much more than simply an opinion. It was largely based on an academic paper by Alan Blinder and Mark Watson. From the opinion piece:

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.

They had economic data since the FDR era (and the difference would certainly have been greater if Hoover had been included) and there’s no amount of timing or coincidence or measurement that would change the conclusion: the U.S. economy does better under Democratic presidents than under Republican ones. From their report:

The gap exists not only for G.D.P. and jobs but also for incomes, productivity and stock prices. The gap also exists if you assume that a president’s policies affect the economy with a lag and don’t start his economic clock until months after he takes office. Virtually any reasonable look at the data shows a big Democratic advantage.

Perhaps the best summation is the following chart. They primarily looked at two measures of economic wellness, Gross Domestic Product growth and nonfarm job growth. As you can see, the differences are quite (and to me surprisingly) large.

Breaking those two major measurements into a presidential ranking, we get these two charts.

If you clicked on the “six months later” or “year later” you get slightly better Republican results, but there’s still a significant Democratic edge.

Why is there such a gap? Luck and timing don’t explain the differences. The explanation that resonates with me is that Democrats seem more willing to try whatever works to make the economy better, while Republicans seem interested only in tax cuts mostly for the wealthy.