As Michelle Obama turns up the heat on food manufacturers, PolicyLink and The Food Trust have released a report that maps America’s "food deserts" and looks at their lasting effects in rural areas and low-income communities of color.

The report culls research from more than 100 previous studies to bring together the best data available on food access. The findings won’t shock anyone living in one of America’s many food deserts, but they prove Obama’s childhood obesity campaign can’t stop with telling parents to feed their kids better:

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• 23.5 million Americans lived over a mile away from the nearest supermarket in 2009;

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• African Americans were nearly four times as likely to live a food desert as whites;

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• 80 percent of nonwhite residents in Albany, N.Y., can’t find low-fat milk or high-fiber bread sold in their neighborhoods;

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• More than 70 percent of families eligible for food stamps in Mississippi travel at least 30 miles to reach a supermarket.

Mississippi, it turns out, has the highest obesity rate in the nation. But it’s not just Mississippi. Nationwide, geographic barriers to fresh fruits and vegetables bring dire health consequences, as residents of communities without grocery stores are more likely to suffer from obesity, diabetes and cardiovascular disease–all health conditions that disproportionately affect African Americans in particular.

Michelle Obama has framed her Let’s Move! childhood obesity campaign, unveiled last month, in a way that all Americans can rally behind–not just those who are affected by the problem. That’s good. But yesterday she spoke for the first time directly to food manufacturers about their corporate responsibilities. "We need you not just to tweak around the edges, but to entirely rethink the products that you’re offering, the information that you provide about these products and how you market those products to our children," she said in a speech to the Grocery Manufacturers Association.