What Are Food Deserts? Definition, USDA Criteria & Health Impact, PlainFoodAccess

How the USDA identifies low-access areas, the urban-rural divide in food access challenges, and what limited access to nutritious food means for health across U.S. communities.

National figures from the USDA Food Access Research Atlas (2019) and Census ACS (2024), rendered live from the PlainFoodAccess database.

The Definition

A food desert is a geographic area where residents have limited access to affordable, nutritious food. The term entered mainstream policy discourse in the 1990s in the United Kingdom and was adopted by U.S. researchers and government agencies in the 2000s to describe a specific, measurable problem: communities where the combination of low income and physical distance from grocery stores makes adequate nutrition difficult to achieve.

USDA Low-Access Definition

Low income: Tract poverty rate above 20%, or median family income below 80% of area median
Urban low access: More than 1 mile from nearest supermarket
Rural low access: More than 10 miles from nearest supermarket
Population threshold: At least 500 people or 33% of the tract affected

Both the income and distance conditions must be met for a census tract to qualify as a food desert under USDA methodology. This dual criterion distinguishes genuine food deserts from areas that are simply remote but economically self-sufficient.

How the USDA Identifies Low-Access Areas

The USDA Economic Research Service maintains the Food Access Research Atlas, which maps food access conditions across more than 72,000 census tracts in the United States. The Atlas was last fully updated in 2019 and uses store location data from the USDA's Supplemental Nutrition Assistance Program (SNAP) retailer authorization list, a comprehensive database of authorized food retailers.

Distances are calculated from the population-weighted centroid of each census tract to the nearest qualifying supermarket. This approach captures typical travel distances for tract residents, though it cannot account for residents at the edges of large rural tracts who may live much farther from food sources than the centroid suggests.

The Atlas also offers alternative distance thresholds, half a mile for urban areas, 20 miles for rural areas, and a low-vehicle-access modifier, allowing analysts to examine food access under different assumptions.

Urban vs. Rural Food Access Challenges

Food access challenges in cities and rural areas share a root cause, economic barriers and geographic distance, but their practical expressions differ significantly.

Urban Food Deserts

Stores may be present but unaffordable
Grocery stores avoiding low-margin neighborhoods
High reliance on corner stores and fast food
Transit-dependent residents limited by what they can carry
Concentration in historically disinvested neighborhoods
"Food swamps" - abundant junk food, scarce nutrition

Rural Food Deserts

Physical distance is the primary barrier
10+ mile trips to the nearest grocery store
Vehicle access essential but not universal
Store closures shrinking options in small towns
Dollar stores often the only nearby option
Larger absolute geographic coverage

Rural counties in the Mississippi Delta, the Texas colonias along the border, tribal lands in the Southwest and Great Plains, and Appalachian communities show some of the highest rates of food desert conditions nationally. These areas combine extreme distance, high poverty, low vehicle ownership, and limited public transit.

Relationship to Health Outcomes

The public health case for addressing food deserts rests on a documented association between limited food access and worse health. Counties with high low-access populations tend to show elevated rates of chronic disease, particularly obesity, type 2 diabetes, and cardiovascular disease, compared to counties with comparable income levels but better food access.

The causal pathway is not simple. Access to stores is necessary but not sufficient for dietary improvement. Price, cultural food preferences, time constraints, cooking knowledge, and the marketing of ultra-processed foods all mediate how people eat. Research has found that when new grocery stores open in food deserts, diet quality improves modestly at best unless accompanied by nutrition education and economic support.

This means food desert conditions are better understood as one dimension of broader food insecurity, which encompasses both the physical availability of food and the economic and structural capacity of households to obtain it.

Key takeaways

A food desert requires both conditions: low income and low access, meaning more than 1 mile from a supermarket in cities or 10 miles in rural areas.
Roughly 1 in 16 Americans lives in a census tract the USDA designates a food desert. Worst food deserts
Distance alone is not the whole story: income and vehicle access decide who can actually reach fresh food.

USDA low-access figures reflect the 2019 Food Access Research Atlas; socioeconomic context is the latest Census ACS 5-year (2024).

Frequently Asked Questions

What is the official USDA definition of a food desert?

The USDA defines a food desert as a low-income census tract where a substantial share of residents, at least 500 people or 33% of the tract population, live more than 1 mile from a supermarket in urban areas, or more than 10 miles in rural areas. Both the income and distance criteria must be met for a tract to qualify.

How many Americans live in food deserts?

USDA estimates that roughly 18 million Americans lived in low-income, low-access census tracts as of the most recent Food Access Research Atlas update (2019). This represents about 6% of the U.S. population. The actual number fluctuates as stores open and close and as income levels shift.

Are food deserts worse in cities or rural areas?

Both settings face food desert challenges but for different reasons. Rural food deserts are driven primarily by distance, stores simply are not nearby, and long trips by car are required. Urban food deserts often involve stores being nearby but unaffordable, or neighborhoods losing grocery stores due to lower profit margins. Rural food deserts tend to be geographically larger; urban food deserts affect more people in absolute numbers.

Does living near fast food make a food desert worse?

The term "food swamp" describes areas with an abundance of fast food and convenience stores but few supermarkets. Some researchers argue food swamps are a more precise description of many urban low-income neighborhoods than "food desert." The USDA Atlas focuses only on proximity to supermarkets, not the ratio of healthy to unhealthy food options nearby.

How do food deserts affect health outcomes?

Research links food desert residence to higher rates of obesity, type 2 diabetes, hypertension, and cardiovascular disease. The mechanism is not simply about what is available, cost, time, cultural food preferences, and cooking knowledge all mediate the relationship. Studies show that simply opening a new grocery store in a food desert does not automatically improve diets, suggesting systemic interventions are needed.

Can food banks and community gardens solve the food desert problem?

Food banks and community gardens provide valuable supplemental support but are generally insufficient to resolve food desert conditions at scale. Food banks depend on donated supply, which is unpredictable. Community gardens address fresh produce but not the full nutritional spectrum. Policy-level interventions, store incentive programs, SNAP expansion, transportation improvements, are necessary alongside these local efforts.