Yesterday, the Treasury came out with a study that showed income mobility has remained unchanged (that’s “not gotten worse” to you John Edwards et al.). I don’t think it paints quite as dreamy a picture as the Wall Street Journal does, but I do agree with their conclusion that the economic case for much of the populism we hear these days is much weaker than many would like us to believe. The Journal’s editorial has a lot of details. But here’s the Treasury Department’s press release:

Treasury Releases Income Mobility Study Washington DC–The Treasury Department today released a study on income mobility of U.S. taxpayers from 1996 through 2005. The study showed that, just as in the previous 10-year period, a majority of American taxpayers move from one income group to another over time. The study also recognizes that the dynamism of the U.S. economy significantly contributes to income mobility. The key findings of the study included: Income mobility of individuals was considerable in the U.S. economy during the 1996 through 2005 period with roughly half of taxpayers who began in the bottom quintile moving up to a higher income group within 10 years. About 55 percent of taxpayers moved to a different income quintile within 10 years. Among those with the very highest incomes in 1996–the top 1/100 of one percent–only 25 percent remained in the group in 2005. Moreover, the median real income of these taxpayers declined over the study period. The degree of mobility among income groups is unchanged from the prior decade (1987 through 1996). Economic growth resulted in rising incomes for most taxpayers over the study period: Median real incomes of all taxpayers increased by 24 percent after adjusting for inflation; Real incomes of two-thirds of all taxpayers increased over this period; and Median incomes of those initially in the lower income groups increased more than the median incomes of those initially in the high income groups.