Using difference-in-difference and regression discontinuity techniques, we find that US states governed by Democrats and those by Republicans perform equally well on economic, education, crime, family, social, environmental, and health outcomes on the timeline introduced by elections.There are a few things one might say about this. The first would be that 2-4 years is not enough time for most government actions to have a measurable impact. Of course, that means voters considering whether to (say) re-elect a governor have no real basis for judging. Another would be that real power in this country is at the national level, so there just isn't much governors or state legislators can do to change the economic fundamentals.
I think this is a sign that the power of any government to change society is limited. It may be easy enough to wreck things, but making them better is just very hard.