DETROIT–Businessman Matt Allen crosses Warren Ave. in lower east Detroit and wades into a neighbourhood.

Houses and a high school once cluttered this block. Now, there is nothing but calf-high grass and a few scruffy trees as far as you can see. He is looking for houses.

"On that block there is one," he says, pointing to a white clapboard house with a green Ford parked out front. Its tires are gone, its back window smashed.

"On the next block there is none. On that block there is none. On that block there is none. On that block there are three."

Behind him, a rust-coloured cigar factory slumps empty, its windows broken. A few blocks down there is a store, but it's boarded up. A man sits with a pit bull on the steps of a dilapidated house next door. Its windows are covered with plywood.

"You'll see a house over there that looks pretty good. But look closer. There's a hole in the roof," Allen says.

A whisper of sidewalk peeks out from beneath the grass. A brown hawk flies overhead.

If you couldn't see the letters "GM" on the top of a tower in the distance, you'd think this was the country. But it's central Detroit – the equivalent of Leslieville in Toronto.

"From McDougall to Chene St., from Warren all the way to Forest Ave., this is 35 contiguous acres and there are five structures on the whole thing," Allen says. "See what I'm saying? It gets real easy, real fast to do the math."

The math adds up like this – Detroit was built for 1.8 million people. Now, half that number live here. Every third house is gone or empty. The former residents are not coming back.

Instead of building yet another flashy casino, Allen is pitching a radical – and highly contentious – solution. Empty whole parts of the city, dig up the concrete, yank down the light poles, and reclaim what was here before a guy named Henry Ford moved to town: farmland.

"This is relatively fertile clay loam," says Michael Score, an agriculture adviser with Michigan State University. It's perfect, he says, for high-end horticultural crops.

Score has drafted a business plan for Hantz Farms, Allen's company. He spins around the field, describing what we'd see standing here in three years. A number of greenhouses growing cucumbers, lettuce and tomatoes. Rows of strawberries and raspberry bushes, where Detroiters will pick their own quarts. Apple and cherry trees. A wetland. A field of sunflowers. A block of Christmas trees.

What about those five houses?

"If someone doesn't want to move, we'll farm around them, just like a farm in the country would," Score says.

This is not some urban planning student's master's thesis. Allen says they've already begun assembling land to become the biggest urban farm in the world, to the horror of local activists.

The Hantz plan is to convert 2,024 hectares of mostly abandoned land into 120-hectare farming "pods" across the city – each roughly the size of Canada's Wonderland.

The farms would provide fresh fruit and vegetables to a city starved for them. It would offer much-needed jobs to Detroiters. And, most important to a city facing a $300 million deficit, it would cut out whole garbage truck routes and police patrol zones – costly budget items.

Urban farms would shrink the city in chunks, cutting out whole neighbourhoods like holes in a block of Swiss cheese.

"How do you take a crippled, post-industrial juggernaut and turn it into something else?" Allen says.

His answer is farm it.

"We're creating a new model for 21st century cities."

Detroit might seem an unlikely champion of urban agriculture, as the birthplace of the automobile and its farm-devouring offspring – urban sprawl.

But, it has become ground zero for North America's local food movement.

Last year there were roughly 550 gardens in the city's urban farming network. This year there are more than 850.

Driving around the city, you can see everything that will make up your dinner – chickens, goats, mushrooms, plum trees, honeybee hives. I passed a whole block growing shoulder-high corn. A horse grazes outside a barn behind a high school. Edith Floyd parks her tractor behind her house – 12 kilometres from city hall, where bureaucrats are scrambling to catch up with the collard greens sprouting on street corners.

Here, a locavore doesn't eat food that's travelled 100 kilometres. She eats food that's travelled 10.

"I picked these this morning," Floyd says, carrying a laundry hamper filled with watermelons to her stand at the Wayne State University farmers' market. The chalkboard propped in front reads "Grown in Detroit."

It's enough to make Michael Pollan, author of local food manifesto The Omnivore's Dilemma, swoon.

Why Detroit?

The answer becomes clear a few minutes after pulling off one of the multiple interstate highways that are the city's equivalent to subway lines.

You feel like you've dropped into Miss Havisham's dark, cobwebby parlour in Dickens' Great Expectations – the uneaten cake an earthy mound on the dusty table, still waiting for the groom decades later.

Whole streets of once-ornate houses are collapsing. Sprawling factories are fenced up, windows shattered. You can see through the abandoned train station in the heart of the city. Kids in school uniforms walk through pastures that yawn between the houses left standing.

While neighbours wait months for street parking permits in Toronto, Detroit has nothing but space.

Even the mayor, Dave Bing, has called half of Detroit vacant.

Once a symbol of industry, the Motor City is now a model for deindustrialization.

It's been shrinking since the 1950s, when the Big Three auto companies were still raking in profits and art deco bank towers crowded downtown. The cars that made Motor City also killed it, speeding inhabitants past the city-limit signs to its leafy suburbs even before the race riots of 1967. After the city burned for a week and 43 people died, there was a stampede to get out. Detroit became a doughnut long before anyone had heard of the Wal-Mart effect.

What's left today is in tatters. Detroit boasts one of the highest crime rates of any American city. Around half of Detroiters aren't in the labour force. According to the Detroit Literacy Association, 47 per cent of the population can't read or write.

Most of the city is a food desert, where residents buy provisions in tins from convenience and liquor stores. There's not a chain grocery or big box store left in all the 357 square kilometres of Detroit. That means to buy even basic supplies, like a bath towel, you have to leave town.

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"There used to be a Polish-Italian bakery there," Mark Covington says, pointing to his patch of broccoli and squash across the street. He's sitting in the window of a hollowed-out home where only two years ago, his kindergarten teacher lived. Since she moved to a nursing home, "scrappers" have broken in and stripped away every bit of metal – the copper wires and pipes, the grates, the doorknobs.

A truck roared up at night, attached chains to the metal bars that still guarded the windows, and pulled them down.

"This was a nice mixed white-black neighbourhood when I was growing up," says Covington, 37. "People started leaving."

Two years ago, after losing his job as an environmental technician, Covington spent a week hauling garbage off the lots beside his home. He then planted boxes of vegetables where neighbours once lived. He named it the Georgia Street Community Garden and invited passersby to tuck in.

"People around here don't have lights or gas," he says, waving to a woman who has stopped to pick some cherry tomatoes. "So what was better to grow – flowers or vegetables?"

A woman up the street started sending her foster kids to help, and a movement was born. Covington erected four white boards to show movies on Saturday nights. He brought in chairs for reading sessions. He started a backpack program and hosted a harvest dinner for 90 neighbours.

Last year, he bought his old teacher's home and the derelict store next door for $1 from the city, and $4,000 in back taxes. He plans to refurbish it into a community centre.

"We're not just into farming. We're into community self-determination," says Malik Yakini, one of the leaders of Detroit's nascent farming movement. The self-described "social architect" runs an Africentric school and chairs the Detroit Black Community Food Security Network. He talks about food justice – where the community reaps both the nutritional and financial rewards of the food it buys.

His D-Town Farm spans two acres of city parkland on Detroit's western edge, where little bungalows with rusted awnings still line wide streets and a faded ice cream truck does laps of the yellowing boulevard. The volunteer team running it sells its leafy greens and radishes to local restaurants and farmers markets. Next year, it plans to hire two permanent employees.

"We're trying to create an economic model, to show how agriculture could contribute to the economic recovery of Detroit," Malini says, pushing into the brush to reveal a plastic greenhouse where oyster mushrooms will soon grow.

That model doesn't include agribusiness. Replacing General Motors with Cargill isn't the answer, he says.

"We're activists. We're concerned with the health, vitality and well-being of the black community generally. This is one part of a larger picture. So any proposal that brings in the corporate sector and disempowers community is problematic for us," says Yakini, who spearheaded the just-formed Detroit Food Policy Council. "We're much more in favour of smaller scale community-operated projects where people themselves have a vested interest and profit from the sale of the produce."

Go to Europe, and you'll trip over the remnants of all kinds of empires. After the fall of the Berlin Wall, the German government moved residents to concentrated areas in cities like Leipzig and turned off the lights elsewhere.

But in North America, where people spend more time every year commuting to work than vacationing, the idea of planning decline is foreign.

"In the U.S., everything is about reaching the next frontier. Growth is progress," says Karina Pallagst, director of the Shrinking Cities in a Global Perspective program at the University of California at Berkeley. "So talking about shrinking is taboo. It's a very painful insight to say we have to cut back."

Still, there are some local models. Facing a population a third the size of its glory days, former steel hub Youngstown, Ohio, has offered to move residents out of dying neighbourhoods into denser ones, where city resources are concentrated. It plans to demolish leftover homes, yank up street lamps and let nature take over.

"It's like taking a segment of an orange out," says Joe Berridge, a partner with Toronto's Urban Strategies, which helped draft Youngstown's "right-sizing" plan.

Flint's former acting mayor, Michael K. Brown, recently spoke about following suit and "shutting down quadrants of the city."

While running for mayor last spring, Bing raised the prospect for Detroit.

"We've got limited resources as a city," his spokesperson Edward Cardinas says. "We're tying to figure out how to keep providing services."

What's different, in Detroit's case, is the role of farming.

City planning officials have struck a working group to craft a vision for "agricultural urbanism" and corresponding legislation. As it stands, all farms are technically illegal. But facing a homicide a day, the city has been preoccupied. Now, it is wondering if the ground beneath the crumbling pavement could be part of the solution.

The Hantz farm proposal is on Mayor Bing's desk. He'll get to it once he figures out the budget, Cardinas says.

The potential is inspiring. A recent study by Michigan State University sustainable agriculture professor Michael Hamm shows that by growing about 5 per cent of the extra fruit and vegetables Michigan residents should be eating to meet health standards, the state's economy would gain $200 million and more than 4,000 jobs. Much of that produce could be grown in Detroit – which by his calculations has 4,800 acres of vacant land, not including parks or right-of-ways.

"There's a huge opportunity," Hamm says. "The lesson then is we can carve out green space and not think of agriculture as an outlying activity to cities. It will be an integral component of a green city in the future."