The Eroding American Middle Class

Anti-declinism easily shades over into complacency, a sentiment we cannot afford. Especially now, as the basis of our society, and of stable and decent political communities generally—a thriving and self-confident middle class—is eroding. Worse, either we don’t know what to do about it, or we don’t care enough to try.

In 1971, according to the Pew Research Center, 61% of all adults lived in middle-income households. By 2011, the middle-income share had fallen to 51%, while the lower- and upper-income sectors grew. Median household income in 2011 was not significantly higher than it had been in 1989. Because upper-income households fared much better during those four decades, their share of total household income increased by 17 percentage points—to 46% from 29%—while the middle-income share fell by 17 points, to 45% from 62%.

These economic trends have social consequences. A recent study by Cornell University researcher Kendra Bischoff and Stanford’s Sean Reardon finds that the share of families living in middle-income neighborhoods declined to 42% from 65% between 1970 and 2009. At the same time, the shares of families living in affluent neighborhoods and in poor neighborhoods more than doubled. Segregation along lines of income grew in each of the past decades, with the fastest growth coming between 2000 and 2009. This trend is not restricted to white Americans. In fact, segregation by income among black families grew four times as much as for whites, and Latino income segregation also increased more sharply.

In sum, the middle class is shrinking and hard-pressed to keep its head above water, while upper- and lower-class Americans are increasingly likely to live in geographical concentrations of wealth and poverty.

if more-advantaged families no longer share social environments and public institutions with less-fortunate families, the better-off may reduce their support for the programs and activities—such as schools, parks and public transportation—in which Americans participate across income lines, a shift that may have “far-reaching consequences” for the rest of society.

In his latest and best book, “Coming Apart,” Charles Murray explores (and worries about) the same question: What does it mean for American society if members of the growing upper-middle class are economically, culturally and geographically isolated from the rest of their fellow citizens?

I worry about all this for the reasons Aristotle offered more than two millennia ago: Societies where the middle class dominates are the most likely to be stable and decent. The wealthy tend to be arrogant and heedless; the economically insecure, resentful and destructive. By contrast, Aristotle observed, members of the middle class tend to have more moderate desires, they are more open to reasonable persuasion, and they are more likely to be linked to one another by ties of civic affection.

More From The Wall Street Journal (subscription required):