 The pre-tax real income growth rate for the wealthiest 40%, 60%, and 80% of population was higher under the Democratic administrations than it was under the Republican administrations in this time period.The United States was more equal and growing wealthier, based on income, under Democratic Presidents from 1948-2005 than it was under Republican Presidents in the same time period.Additionally, Bartels believes that the reduction and the temporary repeal of the estate tax also increased income inequality by benefiting almost exclusively the wealthiest in America.