Food Environment – Low Food Access

Methodology

This indicator reports the percentage of population without access to a supermarket or large grocery store. Census tract-level data was acquired from the USDA Food Access Research Atlas (FARA) and aggregated to generate county and state-level estimates.

The Food Access Research Atlas provides data which is derived from the analysis of multiple datasets. First, a directory of supermarkets and large grocery stores within the United States, including Alaska and Hawaii, was created by merging the 2019 STARS directory of stores authorized to accept SNAP benefits and the Trade Dimensions TDLinx directory of stores. Stores met the definition of a supermarket or large grocery store if they reported at least $2 million in annual sales and contained all the major food departments found in a traditional supermarket, including fresh meat and poultry, dairy, dry and packaged foods, and frozen foods. The combined list of supermarkets and large grocery stores was converted into a GIS-usable format by geocoding the street address into store-point locations. Population data are obtained at the block level from the 2010 Census of Population and Housing, while data on income are drawn at the block group-level from the 2014-18 American Community Survey. Distance to nearest supermarket was determined for population blocks. These numbers and shares are then similarly aerially allocated down to the ½-kilometer-square grid level. For each ½-kilometer-square grid cell, the distance was calculated from its geographic center to the center of the grid cell with the nearest supermarket. Then, the number of households and population living more than 1, 10, and 20 miles from a supermarket or large grocery store was aggregated to the tract level and divided by the underlying population.

Rural or urban status is determined using population size. A census tract is considered rural if the population-weighted centroid of that tract is located in an area with a population of less than 2,500; all other tracts are considered urban tracts. Low-income is defined as annual family income of less than or equal to 200 percent of the Federal poverty threshold given family size.

For more information, please refer to the Food Access Research Atlas Documentation.