The Angry Bear has a fascinating post on Tax Rates and Economic Growth:  A Look at the Data on Marginal Tax Rates, Capital Gains Tax Rates, and Real GDP per Capita

This post looks at the relationship between tax rates and economic growth. … Here’s the plan… First, look at how the top marginal income tax rate, the bottom marginal income tax rate, and the top capital gains tax rate evolved over time beginning in Ike’s term graphically. Next, look at the growth rate of real GDP per capita observed at these different tax rates. Where possible, when a “maximum” or optimal point is uncovered, use correlations between tax rates and growth rates to confirm whether that point truly is a maximum. …

So… what can we conclude from all this? Well, there isn’t much evidence that cutting tax rates, at least to high income earners and on capital gains, will lead to faster growth. In fact, it would seem that since Nixon’s time, tax rates have been below the "optimal" level for generating growth, possibly even leading to slower growth over the past thirty five years or so. This post may go some way toward explaining why since Ike took office, Democratic Presidents have generally produced faster rates of growth in real GDP per capita than their Republican counterparts. Some time soon I’m going to look at that in more detail.