Most debate on Detroit so far has discussed how that city, once the car capital of the world, became the urban ruin it is today. Less asked is the real question: What in the world do we do now for or with Detroit? Does it have a future? Should it have a future? What, if anything, does the rest of the United States owe Detroit and its people? And how should we think about Detroit?

These are important questions, because they go beyond Detroit. The Motor City is only the biggest of a number of post-industrial Midwestern cities that have been dying for years. These include other auto-making cities like Flint, Michigan, or steel centres like Cleveland and Youngstown in Ohio, or Gary in Indiana.

All have lost more than half their population. All have the highest unemployment rates and highest dropout rates in the nation. All existed to serve an industry or company that has gone away. All survive almost as archaeological sites, with streets of ruined homes and downtowns, once humming, that echo eerily in their emptiness.

All except Youngstown are majority African-American. As with so many American issues, race is the background noise that can drown out all else.

The details of Detroit’s 60-year decline are well known by now. All the usual suspects are guilty as charged. They include the incompetence of the car companies, the unaffordable victories of the labour unions, the lack of a diversified economy, massive political corruption, white flight, black misrule, ruinous race riots, the invasion of Japanese auto companies, and, now, globalisation.

Recently, the state of Michigan took over the city and appointed an emergency manager, leaving city officials with offices but no power. Faced with $18 billion in civic debt and no way to pay it, the emergency manager put Detroit into bankruptcy. So far, no one has been paid, but bankruptcy lawyers and consultants have already charged the city nearly $20 million for their high-priced labour. Creditors have even suggested selling off the Van Goghs and Monets in the Detroit Institute of Art to pay down the debt.

In the meantime, Kwame Kilpatrick, the next-to-last mayor, is about to start a 28-year prison sentence for corruption.

That’s where Detroit stands, or rather, staggers.

So, what now?

Naturally, Detroiters hope that the state or federal government will ride to the rescue, as Washington did with the bailout of the auto companies in 2009. The Obama administration has offered $300 million in aid, which amounts to a few coins in the city’s begging bowl.

Which brings us back to the original question: what, if anything, do the state and the country owe Detroit? And how should we think about Detroit?

Detroit, like almost every town and city, exists for some economic reason. Every place began life as a mining town, or a farm town, or a port, or a factory town. Basically, cities are born as labour pools.

If the economic reason is strong enough, people who came to work stay to build houses and schools and churches. Some places become economic powerhouses and become real cities, with universities, theatres, museums like the Detroit Institute.

But in economics, nothing lasts forever. Sooner or later, the mine plays out or the port silts up or the factory closes. When that happens, the town or city must reinvent itself, must find a new economic raison d’etre.

The great cities of history have reinvented themselves time and again. Other cities failed to do so, and either vanished or became backwaters.

The Midwest today is littered with old factory towns, basically unemployed, shrinking, and shriveled. They won’t disappear, of course, but they’ll become backwaters, losing their best young people, occupied by the poorest and least educated who wash up there because they can’t afford to live anywhere else.

That describes Detroit today.

The city, which once had 2 million people, holds only 700,000 today, and is shrinking fast. At least half are unemployed. Crime and drugs predominate. Only one in four boys graduates high school in the required four years. Virtually none emerge with skills tuned to the global economy.

In short, it’s a toxic place to live or raise children.

Amid the wreckage, life stirs. Young artists attracted by cheap rents are moving in. Unemployed Detroiters whose ancestors fled the sharecropping economy of the South are digging up vacant lots to plant subsistence-level urban farms. There’s a small gambling-based entertainment zone called Greektown: three of Detroit’s 20 biggest employers are casinos.

Most ambitiously, a local businessman, Dan Gilbert, has moved the headquarters of his company, Quicken Loans, into downtown Detroit. In addition, he has invested $1 billion already into downtown redevelopment and promises a light rail system and other projects.

Some of this will take root. It will take more than philanthropy, but Gilbert may revive the two square miles of downtown. Other entrepreneurs, attracting by the cheapness or challenge, will move in.

The other 140 square miles of the sprawling, emptying city will be largely abandoned. Detroit is a pioneer in what has become known as the “shrinking city policy”. Empty homes will be razed, police stations and schools will vanish, neighbourhoods will be returned to forest and parkland. This will take a long time, plus money: it’s surprisingly expensive to tear down a city.

The goal now should not be to prop up the existing city and support its 700,000 residents. The realistic goal is to shrink the place to a size, maybe 200,000 or so, that can live decently on whatever economy emerges from the ashes.

So the answer to our question — what does America owe Detroit — is: not much. In these straitened times, the country and Michigan have vital needs — in infrastructure and education — but a limited amount of money that can be better spent somewhere else than in Detroit.

Most Detroiters should be encouraged to leave. The state should help the city work out its bankruptcy. Beyond that, Detroit should be left to create its own future.

The rest is archaeology.