Around 15 percent of the world's food is now grown in urban areas, says the U.S. Department of Agriculture. But the figures for the U.S. are much lower. The city of Cleveland, for instance, produces just 1.7 percent of its food in urban farms and community gardens—and Cleveland is actually more progressive than most American cities, says Parwinder Grewal, PhD, professor of entomology and director of the Center for Urban Environment and Economic Development at Ohio State University.

Compare those numbers to a place like Cuba, where nearly 100 percent of the country's fresh fruit and produce are grown within the country's borders, and the food is almost entirely organically grown. "Cuba has devoted a lot of space to urban agriculture and made an effort for many, many years to grow food locally," says Grewal, because trade embargoes prevented the nation from importing food, and the dissolution of the Soviet Union left its citizens unable to import oil for fertilizers and pesticides. Despite the problems Cuba has with a dictatorial government, its citizens enjoy abundant access to fresh, organic, local food.

Even beyond access to fresh food, "urban agriculture can bring lots of jobs and money to local communities," says Grewal. He's has just published a study in the journal Cities showing how economically beneficial urban farms can really be.

The details: Grewal's research focused on Cleveland, an industrial city that has been walloped by the loss of manufacturing jobs, located in a state with the seventh-highest home foreclosure rate in the country. All that adds up to about 3,000 acres of vacant lots begging to be used. Grewal and his study coauthors used computer modeling to calculate how much food could be produced within the city limits, based on crop yield, average per-person food intake, and three different levels of land use.

In their first scenario, in which 80 percent of every vacant lot was converted to raising produce and backyard chickens, the authors calculated that Cleveland residents could generate between 22 and 48 percent of the fresh produce they consume, 25 percent of the poultry and eggs needed, and 100 percent of their honey demands (Cleveland is also one of few cities that allows for urban beekeeping). In scenario two, the researchers added 9 percent of each "occupied lot," as in home vegetable gardens or food grown on office building property, raising totals to 31 to 68 percent of fresh produce and 94 percent of poultry and eggs. In the last scenario, they added 62 percent of every commercial rooftop in the city, and they calculated that the city could supply itself with between 46 to 100 percent of its fresh produce, along with the same percentages of poultry, eggs and honey as in the other scenarios.

The city currently spends $115 million fresh fruit and vegetables, poultry, eggs, and honey. "Our study indicates that the city can prevent economic leakage anywhere from $27 million to $115 million annually by increasing its production of fresh produce, poultry, and honey," Grewal said in a statement accompanying the article. That’s $115 million that could be spent on other forms of economic and job development, he adds.

What it means: First lady Michelle Obama may have reinvigorated the backyard gardening movement with her organic White House garden, and we're beginning to reach the tipping point for larger-scale urban agriculture programs that spread beyond backyards, says Grewal. In the same way that demand for organic food has surged in the past decade, "interest in local food has increased substantially over the last four to five years," he says. And what better way to fill that demand than with more urban farms and backyard gardens?

Here are some tips on growing the urban agriculture movement in your own town — or backyard:

• Pay a visit to your city's urban planner. Local policies and government regulations are likely to be the biggest hurdles when it comes to expanding the urban agriculture movement, says Grewal. You've likely heard the saga of the Michigan homeowner who was threatened with jail time for installing a vegetable garden in her front yard, which apparently went against city development codes. Your city planner can fill you in on local ordinances regarding both home and community gardens, and tell you who to contact about using vacant lots for community gardens.

• Hit up a local community group or religious organization. If the government proves too difficult to work with, Grewal suggests contacting a local group that has some undeveloped land it'll let you use for a community garden. "Churches are really common places to install community gardens," he adds.

• Look homeward. As always, your own backyard, if you have one, or balcony, if that's all you've got, is the best place to kick-start your personal local food movement; you can even grow a garden on top of your fish tank. Read our tips for starting a backyard garden, or visit OrganicGardening.com for tips on everything from growing tomatoes in containers to seeding lettuce on a vertical wall.

This article is reprinted with permission from Rodale.com.