PlainFoodAccess

Data Methodology

Data Sources

PlainFoodAccess draws from three federal open-data programs:

  • USDA ERS Food Access Research Atlas (2019 edition): The primary food-access dataset from the U.S. Department of Agriculture Economic Research Service, census-tract classifications combining supermarket proximity with income thresholds, the official federal measure of food-desert conditions. We use the 2019 release (the most recent), downloaded as the public Excel export and aggregated from its ~72,500 tracts to the county level.
  • U.S. Census Bureau American Community Survey (2024 5-year estimates): County socioeconomic context, population, median household income, poverty rate, SNAP participation (table B22010), and household vehicle availability (table B08201). Five-year estimates are used for county-level reliability.
  • USDA FNS SNAP Retailer Locator (current-authorized stores): The per-store list of retailers currently authorized to accept SNAP (EBT) benefits, shown on each county profile grouped by store type. We keep only currently-authorized stores (no end date in the source file) and map each retailer's county/state to a 5-digit county FIPS code.

Download the data: the full county-level dataset is available as a CSV file covering all 3,144 counties (low-access share, food-desert population, SNAP participation, and vehicle access). The source figures are U.S. federal public-domain data; reuse is welcome with attribution to PlainFoodAccess.

Data Vintage

PlainFoodAccess covers 3,144 U.S. counties. Food-access figures come from the 2019 USDA Food Access Research Atlas (the most recent edition; based on 2010 census-tract populations). Population, income, poverty, SNAP, and vehicle-access context come from the Census ACS 2024 5-year estimates. The two datasets carry different vintages and are labeled separately on every page. Thirteen areas, chiefly Connecticut's planning regions (which replaced its counties in 2022) and two re-drawn Alaska areas, have ACS data but no 2019 Atlas record, and are shown as "not available" rather than estimated.

Processing Pipeline

  1. The USDA ERS Food Access Research Atlas 2019 Excel export is downloaded from the ERS website (census-tract level, ~72,500 tracts).
  2. Tract-level indicators are aggregated to each county by FIPS: low-access tract counts (USDA's LA1and10 flag), low-access population (LAPOP1_10), food-desert tract counts (LILATracts_1And10), and low-income low-access population (LALOWI1_10).
  3. The USDA "food desert" designation, census tracts that are both low-income and low-access (more than 1 mile from a supermarket in urban areas, more than 10 miles in rural areas) - is preserved at the county level as a tract count and as the population share.
  4. Census ACS 2024 5-year estimates are joined to each county record: population, median household income, poverty rate, SNAP participation, and vehicle availability.
  5. The USDA FNS SNAP Retailer Locator file is filtered to currently-authorized stores (empty end date) and each retailer's county/state is mapped to a 5-digit county FIPS code, giving every county a real, varying-length list of stores that currently accept SNAP benefits.
  6. State- and national-level figures are computed as population-weighted shares, summing the low-access (or food-desert) population and dividing by total tract population, never an unweighted average of county percentages.
  7. All data is loaded into a structured SQLite database serving county profiles, state summaries, and national rankings.

Food Access Thresholds

PlainFoodAccess uses the USDA's official food access distance thresholds without modification:

  • Urban areas: More than 1 mile from the nearest supermarket or large grocery store
  • Rural areas: More than 10 miles from the nearest supermarket or large grocery store
  • Vehicle access: Half-mile and 1-mile variants are also tracked for households without vehicle access

These thresholds come directly from USDA ERS definitions, no reclassification is applied.

Coverage

  • Counties: 3,144 U.S. counties and county-equivalents
  • States: All 50 U.S. states plus the District of Columbia
  • Scope: U.S. domestic only

Update Frequency

PlainFoodAccess monitors both source agencies for new releases and updates the database within 30 days of each new publication. The USDA Food Access Research Atlas is updated periodically, not on a fixed annual schedule, with the most recent edition reflecting 2019 data. Census ACS five-year estimates are released annually, typically in December.

Like all federal statistical programs, there is inherent lag between the reference period and public release. Food access conditions on the ground may have changed since the most recent data vintage. We display the specific data vintage on every page so users can assess currency for their needs.

Data Accuracy Commitment

PlainFoodAccess presents government data as published, without modification or editorialization. We do not apply custom rankings, composite scores, or algorithmic adjustments to the underlying food access indicators. Where county data is missing or suppressed by the source agency, we display "Data not available" rather than interpolating values or showing zeros that could be mistaken for real measurements.

If you identify a potential data error, please contact us at hello@plainfoodaccess.com. We verify all reported anomalies against the original source data and issue corrections when warranted.

Limitations

  • Food access indicators are measured at the Census tract level and aggregated to counties, tract-level variation within a county is not visible in county profiles.
  • The USDA food desert definition uses straight-line distance to supermarkets, not actual travel time or transit access. Real-world travel barriers may be more severe than distance alone suggests.
  • SNAP participation data may lag behind current conditions due to federal reporting timelines and annual publication cycles.
  • Supermarket locations used in food access calculations come from USDA sourcing and may not reflect store openings or closures since the most recent Atlas release.
  • The food desert framework focuses on proximity to supermarkets and does not account for food quality, pricing, cultural food availability, or informal food networks such as community gardens and food pantries.
  • PlainFoodAccess is not affiliated with the USDA, Census Bureau, or any government agency.