These days, it can feel like the entire city of Suffolk is located in a desert.

Actually, it’s just the downtown area that is a desert — a food desert, to be more precise — according to the U.S. Department of Agriculture’s Economic Research Service.

A new study released by the service pinpoints “food deserts” across the United States. Food deserts are census tracts that are low-income and have low access to a large grocery store.

In Suffolk, two census tracts qualify as food deserts. One stretches from Carver Cemetery on East Washington Street to the Suffolk Golf Course on Holland Road and encompasses much of the core downtown’s residential area. Another tract, adjacent to the first, covers an area that stretches from John F. Kennedy Middle School south and west, covering Booker T. Washington Elementary School and its surrounding neighborhoods.

The research was done because of a congressional mandate to do a study on food access and how it contributes to the rising obesity epidemic.

“All of this is coming up because of obesity concerns,” said Michele Ver Ploeg, an economist with the Economic Research Service.

To be low-income for the purposes of the study, at least 20 percent of the census tract’s residents must live under the poverty line, or the median family income must be at or below 80 percent of the area’s median family income.

To qualify as a low-access community, at least a third of the census tract’s population must reside at least a mile from a large grocery store, or at least 10 miles in rural areas.

According to Ver Ploeg, the data shows that there is an association between being far from a grocery store and having obesity-related health issues. However, studies have yet to find any evidence that shows the health problems are caused by the lack of food access.

“It’s all correlational,” she said. “There’s not much causal evidence. What’s causing what is still unclear.”

Although there doesn’t seem to be a dearth of grocery stores downtown, given that there are several on Main Street and a Fresh Pride on East Constance Road, Ver Ploeg pointed out that most residents of the two census tracts are probably at least a mile from any of the stores.

“If you don’t have a car and you’re more than a mile from a supermarket, that’s a hardship,” Ver Ploeg said.

Governments at all levels can use the data to create programs to help, Ver Ploeg said. For instance, Baltimore recently instituted a program that allows patrons to order their groceries at the local library and return on a designated day to pick up their order.

But other than that, most places are at a loss for ideas, especially with a lack of funding, Ver Ploeg said. For now, grocery store chains simply are encouraged to open locations in the food desert areas.

The data used in the survey came from 2000 census data and a 2006 list of supermarkets. Now that 2010 census data is finalized, Ver Ploeg said, the research will be updated next year.

To view the food desert locator, click here.