Although it is well known that marginal income tax rates vary with inc
ome, few economists have studied the effect on real GDP of the distrib
ution of marginal income tax rates, This omission is probably because
data on the distribution do not exist. We remedy this shortcoming by p
roviding a computer program that calculates marginal income tax rates
for all income levels for the years 1930 to 1990. We conduct a prelimi
nary empirical investigation into the effect of taxes on economic grow
th. We find that lowering taxes significantly raises economic growth a
nd that changing the tax rate schedule also has significant effects on
economic growth.