(Peyton Craighill / The Washington Post)

The U.S. economy is nearly as unequal now as it was on the eve of the Great Depression, when the wealthiest one percent of families received 20 percent of the national income. To some extent, government policies that didn't exist back then have helped the middle class keep up. Americans, however, have not become more supportive of these policies as the rich have gotten richer, and surprisingly, support has actually declined most among blacks and the elderly -- two groups that depend most on the government to get by.

That's the startling conclusion of a paper being presented Thursday at the Brookings Institution. The authors, Yale University's Vivekinan Ashok and Ebonya Washington and Columbia University's Ilyana Kuziemko, discovered the puzzle in their analysis of several decades of polling data.

Blacks are still far more supportive of governmental redistribution than the population as a whole. The elderly used to be as supportive, but now they are more likely to be opposed. What's more, opposition is growing among these groups to the kinds of redistributive policies that benefit them in particular. Blacks have become more opposed to the idea that the government should help members of racial minorities. The elderly are increasingly adamant that the government should not provide health insurance -- despite their fondness for Medicare, a federal program.

[Related: The racial wealth gap we hardly talk about: What happens in retirement]

The polling data challenges the common-sense idea that voters support policies that are in their material interest, the authors write. Yet there don't seem to be any good explanations for the trends, which are shown in the chart above.

It's not that blacks or the elderly on the whole are becoming wealthier and thus less dependent on government assistance. Black and elderly people were just as likely to change their views on the question whether they were rich or poor. Nor are members of these groups becoming more conservative on other questions.

Since 1978, though, the elderly's views have shifted to the right on the question of whether the government should redistribute income to help the poor by about 60 percent of the difference between the average Democrat and the average Republican, depending on the question being asked. For blacks, the shift has been around a third of the difference. The Washington Post added the most recent polling results from the General Social Survey at the University of Chicago to the data in the paper, and the patterns look like they're persisting.

Another possibility is that older people fear that any new redistributive policies would somehow put Medicare at risk. The elderly are increasingly opposed to the idea of universal health insurance, the authors found. In one recent, separate poll, 93 percent of Americans over the age of 65 claimed not to receive health insurance subsidized by the federal government. That figure suggests older Americans believe that Medicare is something they've paid for, not a subsidy, and if so, maybe they feel that others should have to pay the full cost of their benefits, as well. Older Americans do not pay the full cost, though. Those who turned 65 in 2010 will receive $167,000 in Medicare benefits in exchange for $58,000 in Medicare taxes on average over their lifetimes, according to the Urban Institute.

(Alex Wong) (Alex Wong)

Still, this misperception doesn't explain why the elderly are even less supportive of redistribution than the population as a whole. Nor does it say much about what might have changed their attitudes since 1978.

The Washington Post analyzed the polling data by generation to see whether baby boomers have different views from their parents on redistribution. Support for redistribution declined as members of each generation aged. For example, 51 percent of boomers felt the government should reduce the differences between rich and poor when they were between the ages of 18 and 29, a figure that had declined to 34 percent by the time they were at least 65 years old.

Still, there was also a decline between generations. Boomers older than 65 were less likely than older members of previous generations to support help for the poor.

Differences in the experiences these groups shared might be part of the reason. Those who lived through the Great Depression and World War II might have good memories of President Franklin D. Roosevelt, whose administration created Social Security in 1935, and the G.I. Bill, which helped veterans returning from the war go to college.

President Johnson's Great Society might have been a formative experience for the boomers. Johnson signed the law creating Medicare in 1965, a fact that many people receiving Medicare today seem not to remember. "Keep your government hands off my Medicare" has long been a popular rallying cry for some conservatives opposed to health care reform.

President Obama's health care law is arguably the most significant effort to reduce inequality since Johnson's administration, but it remains to be seen whether the law will change how Americans think about the issue. It's not clear whether current generations, as they age, will continue the trend of declining support for redistribution.

It could be that the elderly are healthier in old age than their parents and grandparents were. People who feel worse overall might be more grateful for help of any kind, including from Uncle Sam. When the authors examined this theory, though, they found that the elderly in other countries were not becoming less supportive of redistribution, ruling out global advances in medicine as an explanation.

Other research has found that blacks, for their part, are much happier now than they were during the days of the civil rights movement. They are also less likely to be living in poverty, and their real wages have improved. That said, blacks are twice as likely to be unemployed as whites, and they still earn about $20,000 a year less on average, as was the case 50 years ago. Whatever the reason, when asked specifically whether the government should do more to help blacks and members of other minorities, blacks have become more likely to say that it should not.

One final possibility comes from Suzanne Mettler, a professor at Cornell University. She has argued that as the government has increasingly relied on obscure provisions in the tax code to distribute benefits, ordinary Americans have become less aware of the benefits that various subsidies bring to their lives. If so, this change could be most pronounced among people who depend more on the government.

Further research might be able to solve this riddle, but for now, the figures raise uncomfortable questions for liberals. Their efforts to establish public support for generous redistributive policies are failing among the groups that have the most to gain from them.

Peyton Craighill and Scott Clement contributed to this report.

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