Where the data comes from

• USDA's SNAP Retailer Locator Historical Data, covering 2006–2025.
• It is a public file. USDA lists every store it has authorized to accept SNAP, with an address and the dates the authorization started and ended.
• We add nothing to it. Every dot on the map is a row USDA published.

What one dot means

• A store that was authorized on 31 December of the year you have selected.
• Move the year slider and the map redraws for that date.
• An authorization is not a storefront. When a record ends, the store may have closed — or it may still be open and simply stopped taking EBT. The file cannot tell those apart, and neither can we.
• Because we use one date a year, 45,704 stores (7.0%) never appear at all. They opened and closed between two 31 Decembers.

How the file was cleaned

• 703,441 rows became 661,456 stores. 37,941 stores hold more than one authorization, because authorizations lapse and restart. Counting rows instead of stores would double-count them.
• We check every location against the borders of the US, its states and its territories. Three kinds of store fall out: 4,542 with no coordinates at all, 40 placed outside the country, and 6 whose coordinates disagree with their own listed state.
• 656,868 stores have a location good enough to map. Of those, 611,164 appear on at least one year.

The three ways a store is labelled

• Store format — USDA's own category, 18 of them, from supermarket to farmers' market. USDA assigns it and it never changes within a record.
• Retailer — we match store names to 289 chains using a hand-checked list, and group those into 13 parent companies. Matching is on whole words, so "Giant" never matches inside "Giants Deli".
• Owner — chain, independent, or unknown: 192,307 / 341,325 / 123,236. A gas-station brand on the sign counts as unknown, not a chain, because a fuel brand is a supply contract and says nothing about who owns the store.

How we check our own work

• The map is rebuilt from the database on every run, and the code refuses to write it unless the counts match the database for all 20 years.
• Store arrivals and departures have to add up exactly, every year, with nothing left over.
• Where a claim depends on stores really closing, we test it against a source outside this file — a company's own reported store count, or the Census Bureau's count of business locations, which counts a store whether or not it takes EBT.

What this data cannot tell you

• Nothing about prices, sales, floor space, or what is on the shelves. A dollar store and a supermarket each count as one dot.
• Nothing about how much SNAP money any store takes in. A 2019 Supreme Court case put those figures beyond public reach.
• Nothing about whether anyone has a car, which is often what decides if a store two towns over is reachable at all.

The long version

Every figure, the pipeline that builds the map, the brand list, and the checks that have to pass before anything is published are all public:

github.com/Data4ThePeople/SNAP_Locations