WASHINGTON - Income inequality has soared to the highest levels since the Great Depression, and the recession has done little to reverse the trend, with the top 1 percent of earners taking 93 percent of the income gains in the first full year of the recovery.
The yawning gap between the haves and the have-nots - and the political questions that gap has raised about the plight of the middle class - has given rise to anti-Wall Street sentiment and animated the presidential campaign. Now, a growing body of economic research suggests that it might mean lower levels of economic growth and slower job creation in the years ahead, as well.
"Growth becomes more fragile" in countries with high levels of inequality like the United States, said Jonathan D. Ostry of the International Monetary Fund, whose research suggests that the widening disparity since the 1980s might shorten the nation's economic expansions by as much as a third.
Reducing inequality and bolstering growth, in the long run, might be "two sides of the same coin," research published last year by the I.M.F. concluded.
Since the 1980s, rich households in the United States have earned a larger and larger share of overall income. The 1 percent earns about one-sixth of all income and the top 10 percent about half, according to statistics compiled by the respected economists Emmanuel Saez of the University of California, Berkeley and Thomas Piketty of the Paris School of Economics.