When I came across a set of 7-Up bottles in a storage area, I learned that they were collected because of their relationship to a nation-wide campaign to adopt the metric system in the late 1970s and early '80s (all of the bottles are either one or two liters in size). But what struck me most about their packaging was not their size, or their experimental shape, but that the bottles were made of glass.

All soft drink bottles used to be made of glass and supermarkets were once a place where empty bottles were returned "for deposit." In the 1950s and earlier, bottlers actually washed the empties and re-filled them. Now, of course, bottles are mostly made of plastic and recycled if it's convenient to do so. Very few states require deposits to be paid on plastic bottles, and because the composition of plastic can vary, recycling it is less straightforward than recycling glass. Plastic is often preferred by producers and consumers, however, for its extreme versatility, lighter weight, and resistance to shattering.

Storage room photo. Even though they are empty, you can see how the heavy glass bottles will leave impressions on the dense foam padding lining the shelf when moved.

Photo from a General Cinema Corporation annual report, circa 1980, when every soft drink bottle on the shelf was still glass. Digital copy courtesy of Dave Aldrich.

Groceries weren't always displayed on such orderly, open-access shelving. Before expansive supermarkets with wide aisles became common, goods were located on shelves behind a counter and retrieved by a store clerk upon request. The version of grocery shopping popular today has a specific name: self-service.

Publix supermarkets showcased their wide aisles and a self-service dairy case by driving a shopped around a new store in a tiny car, circa 1957. Photo courtesy of Publix Supermarkets, Inc.

When the self-service idea was new, a few industries actively promoted it as a way to sell their products to retailers. Manufacturers of shopping carts and open-style refrigerated cases were early proponents of customers serving themselves.

A Frigidaire pamphlet designed for retailers and store managers from 1950. The women in the cover illustration are all wearing white gloves, but handling raw meat worry-free thanks to cellophane. This pamphlet is held in the Smithsonian's collection of trade catalogs.

Another promoter of the self-service supermarket was E. I. DuPont de Nemours & Company. Invested in the production of cellophane since the 1920s, they recognized the many uses for their product in such an environment. DuPont encouraged both retailers and consumers to see cellophane and self-service as appealing, convenient, and profitable.

For shoppers, cellophane advertisements promised greater convenience and cleanliness, without any loss of freedom to see the contents of the package. DuPont believed that if consumers preferred wrapped products and serving themselves, then more store managers would feel compelled to provide it.