The map above shows the county-level results of their analysis, which found that most of the highly insecure counties are in the South. Of the 33 counties with the lowest food-insecurity rates, all but four are in oil-rich North Dakota. Food-budget shortfalls were estimated by using responses to Census questions.

Here’s a look at some of the report’s key facts, figures and charts.

1. Drivers of food insecurity have been rising over the past decade

The insecurity rate was estimated based on related indicators, such as poverty, unemployment and homeownership, all of which have worsened over the past decade.

2. On average, the food-insecure need nearly $70 more for food a month

3. In the counties that have it worst, more than one in five are food-insecure

In the 10 percent of counties with the highest food insecurity rates, some patterns emerged. First, more than one in five residents — 23.4 percent — in these counties was food insecure.

4. Rates can vary nearly eightfold

5. About half of highly insecure counties are rural

Rural counties account for 51.5 percent of the highly insecure counties, but just 42.5 percent of all counties.

6. Insecure counties are concentrated in the South

The South is home to 90 percent of these highly insecure counties, with the largest concentrations in the South Atlantic (Delaware, D.C., Florida, Georgia, Maryland, North Carolina, South Carolina, Virginia and West Virginia) and East South Central states (Alabama, Kentucky, Mississippi and Tennessee).

7. Counties with large minority populations are disproportionately food-insecure

Of all the counties where a majority of residents are African American, 93.1 percent belong to the highly insecure category. In counties that are majority white, just 6.2 percent belong to that highly insecure group.

8. The worst tenth of congressional districts were home to an average insecurity rate of 25 percent

It was as high as 30 percent in Michigan’s 13th district, represented by Democrat John Conyers. Unlike counties, highly insecure congressional districts are more geographically diverse. More than a fourth are in the South Atlantic and just under a fourth are in the East North Central U.S. (Indiana, Illinois, Michigan, Ohio and Wisconsin).

9. Meal prices vary wildly throughout the nation

Food prices can range from as little as $1.93 per meal in Maverick County, Tex., to as much as $5.50 in Crook County, Ore. Local food-cost estimates were based off data provided by Nielsen, which assigns sales of local food items to the 26 food categories defined by the USDA’s Thrifty Food Plan.