Historical data on income in the United States show that both the rich and the poor are getting richer according to Nobel Laureate Robert W. Fogel, using a process called the Gini ratio. Fogel also has shown that a majority of any short-term change in those findings is due to people with higher incomes working more hours than those with lower income!
W. M. Cox and Richard Ali found in their study that the proportion of poor in the U.S. when measured in terms of consumption has falling from 31 percent in 1949 to approx 2 percent by 1989. They also found that only 5 percent of those in the lowest 20 percent of income were still there 15 years later, and 30 percent of those occupied the top 20 percent. This confirms the findings of the Employment Policies Institute