For a society that supposedly is classless, we certainly spend a fair amount of time arguing about class warfare, who is waging it, which way the wealth is flowing, who's rising, who's falling. To hear it from the right field, America's wealth is rushing downward, from the wealthy to the (mostly unenterprising) citizens at the bottom. To left-siders, the wealth is flowing upward, from a squeezed middle class to the (shamelessly greedy) wealthy. We can't have class warfare if we don't have classes -- or can we?I am as partial as anyone to the ideal of up-by-your-bootstraps meritocracy, a classless, caste-less society, in which people can "rise above their stations" (as one might have put at one time) if they work hard enough. But many research studies are finding an American reality now that is just not so. What we have, increasingly, is a society in which economic and social mobility are not as fluid as we might think compared to, say, Britain (Jeeves!), Denmark or Canada.A New York Times article summed up some of those findings last week. One reason for the mobility gap, it suggested, may be the depth of American poverty. Another may be the high premium employers pay for college degrees. The article explained further: "Since children generally follow their parents' educational trajectory, that premium increases the importance of family background and stymies people with less schooling."Last week, too, America's Promise Alliance released two research reports, "The Economic Value of Opportunity Youth" and "Opportunity Road: The Promise and Challenge of America's Forgotten Youth." The Alliance is the national group founded by Gen. Colin Powell and his wife, Alma, to address high school dropout and related issues."Opportunity youth" (as optimistic a name as you are likely to find under the circumstances) refers to the population of young Americans from 16 to 24 years old "who are not enrolled in school, are unemployed and do not have a college degree." They "may have dropped out of high school or college and been unable to find work; may have been involved in the criminal justice system; may have mental or health conditions that have inhibited their activities; or may have care-giving responsibilities in their families."The research estimates there were at least 6.7 million opportunity youth last year, of whom nearly 73 percent "are confident and hopeful they will be able to achieve their goals in life."Where does the confidence come from? Put together the tightening relationship between economic mobility, education and family background, and you have to scratch your head: Is this a mass delusion? How are they going to achieve their goals, whatever those may be?But "opportunity youth" are not so named for their optmism. Economists talk about opportunity costs, the value of alternatives foregone. In "The Economic Value of Opportunity Youth," those costs are tallied to numbing effect. Herewith the researchers' conclusions:--Each year, each 16-year-old opportunity youth imposes a taxpayer burden of $13,900 and a social burden of $37,450. The social burden per youth per year is 75 percent of what the median household earns ($49,500) in a year. Over a lifetime, the taxpayer burden for that single opportunity youth amounts to $258,240 and the social burden is $755,900.--Over the lifetime of last year's cohort of 6.7 million young adults who were out of school and out of work, the aggregate taxpayer burden is calculated to be $1.56 trillion in present value terms. The social burden is put at $4.75 trillion. The study reminds, helpfully, that "these costs roll over each year because each year brings a new cohort of opportunity youth."As economists do, they will argue about metrics and calculations and projections. A layperson need only absorb this one simple realization: The nation is losing in two ways because a large number of its young people are marginalized for reasons that may or may not be their own fault. We lose the full measure of economic and social contributions they might make over a lifetime. And we lose again in paying the expense to carry them along.That's one way to understand the report. Another way, the emphasis of the "Opportunity Road" report, is to consider that these numbers represent potential that can yet be recouped, contributions to society that can yet be made. But only if the nation has a mind to. So now let's talk again about class and warfare.Opportunity youth, as the reports note, are found in substantial numbers across all youth groups. We can ignore them and have ourselves an entrenched, undereducated, unskilled and disaffected "underclass." Or we can seek avenues for them to move up.