BEFORE THE 1930S , shopping carts didn’t exist because nobody needed them. With virtually no home refrigeration except iceboxes, shoppers purchased a day’s worth of groceries at a time, usually at a number of different stores : the fish monger, the greengrocer, the butcher, the baker, and so forth. If you bought more than you could carry, you had it delivered.

Supermarkets changed all that. Their rise was fed by several developments: widespread automobile ownership, which let customers bring large purchases home themselves; household refrigeration, which made once-a-week shopping possible; and the Depression, which increased pressure on retailers to pinch pennies. Supermarkets kept prices low with volume and by eliminating certain services offered by old-style stores: No credit, no home delivery, and customers had to pick out their own purchases instead of requesting items from a clerk.

Sylvan Goldman, who owned a chain of Humpty Dumpty supermarkets based in Oklahoma City, noticed that when customers in his store used handheld baskets, “they had a tendency to stop shopping when the baskets became too full or too heavy.” He told his employees to approach people whose baskets were full and offer to give them a fresh basket while holding the full one at the checkout counter. It was an inefficient solution, and Goldman searched for something better.

In retrospect, a wheeled cart may seem the obvious choice. It wasn’t, judging from some earlier efforts to increase customers’ carrying capacity. One Texas grocery chain tried an arrangement in which customers pushed handbaskets along a waisthigh track in front of the shelves. A store in Boston deployed a motorized conveyor belt. A chain in Houston offered customers the use of little hand-drawn wagons, but the practice never caught on, probably because having more than a few wagons on the premises created a storage problem.

According to the definitive biography of Goldman⁸ The Cart That Changed the World , by Terry P. Wilson—inspiration struck as he worked late in his office one evening in 1936. He looked at a folding chair and had the idea of replacing the seat with two shelves, one higher and one lower than the seat’s usual position, and outfitting the legs with wheels. The shelves would hold shopping baskets, which could be removed and stacked when not in use, and the carts could be folded up for compact storage.

Goldman described his idea to Fred Young, a carpenter and handyman for Goldman’s stores. Young built a prototype from an actual folding chair. The first test was not encouraging. When the cart hit a wooden matchstick on the floor of Goldman’s office, it stopped dead and began to fold. Young eventually assembled a sturdier device designed to carry two 19-by13-by-9-inch wire baskets. Goldman built several dozen and introduced them in his stores with great fanfare in the summer of 1937.

Customers didn’t want anything to do with the carts, even when Goldman hired attractive young women to offer them to people entering the store. In a 1977 television interview with Charles Kuralt, Goldman recalled: “The housewives, most of ‘em, decided, ‘No more carts for me. I have been pushing enough baby carnages. I don’t want to push any more.’ And the man would say, ‘You mean, with my big strong arm that I can’t carry a darn little basket like that?’”

Goldman was undeterred. He hired men and women of assorted ages to pose as customers and use the carts. The ruse worked, and shoppers’ reluctance faded. By the end of the year he had launched the Folding Basket Carrier Corporation to sell his carts to stores around the country. The company has changed hands several times since Goldman sold it in 1961, after his patents had expired; today it is part of UNARCO Industries, Inc. (formerly Union Asbestos and Rubber Company), which is based near Tulsa, Oklahoma. Since the idea was easy to copy, other inventors came up with their own folding or collapsible wheeled baskets, but Goldman’s company dominated the field. Within a few years shopping carts were everywhere.

During the 1940s shopping carts acquired most of the features we are familiar with today. The biggest innovation came in 1947, when carts started to be nested together like spoons instead of being folded up individually and stacked. The trick was accomplished by putting a hinge on the back of the basket (which was no longer removable), allowing it to swing upward, and making the front of the basket smaller than the rear, so one could fit inside another. Employees could now store carts by simply shoving them together, wrangling a dozen or more at once if necessary, and a shopper could easily pull one from the stack, ready to use.

Just in time for the baby boom, the child seat was also introduced in 1947. (The hinged flap that lets an unoccupied child seat serve as a shelf came along five years later.) Before then, small children were often placed in the lower basket of a two-basket cart; a 1940 Saturday Evening Post cover had shown this common but perilous practice. Today child safety belts are standard equipment, largely at the insistence of Wal-Mart in the 1990s.

Nesting carts were invented by Orla E. Watson of Kansas City, Missouri, who filed for a patent on a nesting two-basket version in September 1946. The following spring he introduced prototypes at Floyd Day’s Super Market, in Kansas City, and established Telescope Carts, Inc. Around the same time, Goldman developed a nesting singlebasket version, which he called the Nest Kart, and filed for his own patent. In 1949, after some litigation, Goldman abandoned his claim and agreed to license Watson’s patent. A fullsize modern cart, which sells for about $100, has a capacity of 6.5 cubic feet, not including the seldomused shelf at the bottom of the chassis.

To the casual observer, it looks pretty much the same as one of 50 years ago. Taft O’Quin, vice president of operations at UNARCO, doesn’t disagree. “They’re very similar,” he says. One major difference, he notes, is the finish used to protect carts that are stored outdoors. The standard nickelchrome electroplate finish has been supplanted by baked-on layers of epoxy and polyester, which confer great resistance to rust. Most of the other innovations since the early 1950s, while important, are less noticeable, such as sealed wheel bearings, a unitized frame, nonmarking rubber wheels, and swivel casters.

A majority of the carts sold today have baskets made of corrosion-free injectionmolded plastic rather than wire mesh. These carts, O’Quin says, are favored by many drug chains and other retailers that “don’t want that old grocery-store look.” Plastic baskets are arguably more attractive and definitely more resistant to rust, but they aren’t as durable as wire, and they retain dirt more easily, so many supermarkets still prefer the metal kind.

In keeping with the convention in which computer icons depict the technology they are replacing, the shopping cart has been adopted by online retailers as a means to track and review items selected for purchase. Despite his background in bricks-and-mortar retailing, Goldman would probably have loved the idea: a shopping cart with virtually limitless capacity.