There’s a geography of inequality in modern America and you can explore it in a day’s drive.

Start in Chicago’s glittering Loop, perhaps at the corner of Michigan Avenue and Adams Street, where the fabled Route 66 began. It’s a great neighbourhood, with the Art Institute across the street and the Chicago Symphony a half-block south. This is the way global cities are supposed to look. If America has problems, you can’t see them from here.

Then head south or west along one of Chicago’s expressways named after dead politicians, mostly Democrats. After three miles or so, take an exit ramp into neighbourhoods like Englewood or Lawndale, blighted inner areas holding a black underclass left behind decades ago. It’s OK by day, but don’t go there at night: along with their appalling poverty, these neighbourhoods are the epicentre of Chicago’s current murder epidemic. You’re still in town here, close enough to see the skyscrapers of the Loop, but for the people who live there, that silver city could be a million miles away. This is “traditional” poverty and inequality, rooted both in race and economics, the way it’s been for a half century.

Now get back on the expressways and take them out of town. Drive 100 or 200 miles, into downstate Illinois, or into central Indiana or eastern Iowa or almost any place in Michigan. Take an off-ramp at random, hit the back roads, and roam the old farm and mining towns of the Midwest. These forgotten hamlets are the home of the new underclass, a white underclass this time, a working class without jobs to do, stranded without education or useful skills in a 21st century economy that has no use for them.

This is the urban-rural divide, the new poverty that Americans are just beginning to recognise.

America basically wrote off its inner-city blacks — their unemployment, bad schools, drug use, single-parent households — a generation ago. Now this country is just waking up to the pathology of its new white underclass — the same unemployment, the same bad schools and drug use, the same familial breakdown, the same hopelessness.

New statistics dramatised this situation but got relatively little attention, perhaps because they seem incredible to most Americans. Based on census figures, they showed a decline in longevity among the poorest and least educated Americans. Life expectancy for white men without a high school diploma has dropped by three years since 1990. For white women drop-outs, it’s even worse: down by five years.

This is as nearly bad as the six-year drop in life expectancy for Russian men in the last years of Communism. Even in the black ghettoes of American cities, we’ve never seen anything like this: longevity for black men dropped by a year or two between 1984 and 1989.

Russian men drank themselves to death. The decline for black men in the ’80s was blamed mostly on HIV and homicides. But what’s going on with this new white underclass?

No one knows for sure. My guess would be that much of this is concentrated in rural areas, in the post-industrial Midwest but also in the backwaters of New England, the dying villages of the Great Plains, the impoverished South, inland California, the water-starved wastes of Oklahoma, and the great swath of hillbilly America from Virginia into Oklahoma.

Much of this area, like the Midwest, depended on companies and industries that relied on cheap and unskilled labour and were quick to be outsourced. Drug use — methamphetamine more than heroin — is widespread. County hospitals are closing. Small-town doctors die and are not replaced. One big Walmart can kill off local groceries for miles around, leaving rural people with nothing but a gas station shop where the closest thing to a real meal is frozen pizza. In America’s farm belt, food deserts are common and malnutrition is a serious problem.

It’s hard to imagine two clans more isolated from each other than inner-city blacks and rural whites. But increasingly they share the same pathologies, for the same reason: their jobs went away. The blacks just got there first — four or five decades ago — and now are deep into the generational poverty that awaits the whites who, until recently, could consider themselves middle class.

Many urban whites also have been pushed into poverty by the twin forces of globalisation and automation; even college graduates are stocking shelves or running cash registers to keep going. But as city dwellers, they at least live near supermarkets, hospitals, and the other artefacts of a functioning economy.

The trends for rural Americans point down. All statistics indicate that marriage and family life is good for your health, but no fewer than 54 per cent of high-school dropouts — the same people with shortened life spans — are having babies outside marriage. Banks are the crucial source of funding for local economies but, as online banking grows, big banks are closing their small-town branches. Higher education is a pathway to economic stability but Midwestern states have all but stopped supporting the big state universities that once educated rural students; the universities, strapped for cash, are turning to Asian or wealthy students who can afford the tuition and fees, squeezing out local students who can’t.

Many rural secondary schools, like many inner-city schools, are inferior. Relying on property taxes, their income plunges as property decays and falls off the tax rolls. As population dwindles, schools become empty but old rivalries block the logical solution, which is consolidation. Few rural areas can draw the good teachers or afford the facilities, let alone broadband, that are key to an information-age education.

Ambitious students, mostly from middle-class backgrounds and intact homes, escape rural areas for a good education and a job in the city, just as ambitious black students escape the ghettoes. In both cases, these students vow never to go back.

Behind them they leave the castoffs of the global economy, occupants of the same country, perhaps, but a different universe.