The Ubiquity of Energy-Dense Snack Foods: A National Multicity Study
It looked at over 1000 non-food stores in the US and found that 41% sold candy, soda, chips, and other packaged snacks - mostly within arm's reach of the cash register.
Drug stores and gas stations were fairly flush with the stuff. But creeping up the list were clothing stores, hardware stores, garden supply shops, auto repair shops, book stores, and furniture stores.
Is there such a thing as a snack store anymore?
This was notable: Availability of snack foods did not vary by racial or socioeconomic characteristics. Another of my preconceptions up in smoke. (Another misconception was that people of lower income spent less time preparing meals than their higher-income counterparts. According to the USDA's Economic Research Service, people in lower-income households spent more time preparing meals.)