What Americans eat is shaped substantially by where food can be bought. The mechanisms are logistical, and they operate regardless of what a household knows about nutrition.
Store formats differ in what they stock
Full-service supermarkets carry fresh produce, meat and dairy at volume, supported by refrigeration, distribution frequency and turnover that make perishables viable.
Smaller convenience formats stock shelf-stable products because low turnover makes fresh inventory a loss, which is a business calculation rather than a choice about customers.
Where the nearest store is a convenience format, the available selection sets the ceiling on what a household can routinely eat.
Transportation determines shopping frequency
Households with a car can shop weekly and buy in volume, which lowers unit costs and supports keeping perishables on hand.
Households relying on buses, rides or walking are limited by what can be carried in one trip, which favors dense, durable, lighter items.
Trip frequency also drops when each trip costs an hour or more, and less frequent shopping pushes further toward long shelf life.
Storage capacity is an overlooked constraint
Buying in bulk requires freezer and pantry space, and smaller apartments, shared housing and temporary accommodation often lack both.
Without storage, the savings from larger packages are unavailable, so the same food costs more per serving for the household with less room.
Unstable utilities compound this, since a refrigerator is only useful when the power stays on continuously, and a single interruption can destroy a week of carefully bought food.
Benefits programs interact with availability
Federal nutrition assistance is accepted at authorized retailers, and the density of those retailers varies considerably across neighborhoods.
Farmers markets and delivery services accept assistance in some places and not others, and enrollment requirements differ by state and by market.
Monthly benefit timing also concentrates purchasing into a single period, which interacts with storage capacity in exactly the way described above and pushes households toward durable goods.
Retailers respond to that timing as well, adjusting stock and promotions around the days when benefits load, which shapes what is on the shelf at the moment people shop.
Why access alone does not fix diets
Studies of new supermarkets opening in underserved areas have generally found smaller dietary changes than proponents anticipated.
Price, time, cooking equipment, work schedules and established preferences all continue to operate after a store opens, and access removes only one constraint.
The practical conclusion is that dietary patterns respond to several conditions at once, which is why single-factor explanations of what a community eats tend to be wrong.