You probably give more thought to shopping carts than you might imagine. Pulling one out of the corral, you make a quick assessment of its aisle-worthiness. Shaky steering? Annoying squeak? We've all been stuck with a bad set of wheels because we're in a hurry, or there are no better ones left, and it's not fun. The cart is key to an enjoyable shopping experience.

And retailers know it. Target hired Boston-based Design Continuum to rethink the shopping cart — a big deal in an industry that typically buys generic carts from manufacturers. The result is a good example of engineered mobility. It's made of lightweight recyclable material, with interchangeable plastic parts. Rust isn't a concern, repairs are easy, and scanning cart contents is a breeze. Even the color, Target's trademark cheery tomato red, now plays a starring role.

With a new caster design and less weight, the hyper-maneuverable cart is less likely to damage store shelves or parking lot vehicles. Standard steel carts weigh nearly 70 pounds; plastic ones tend to be 15 to 20 pounds less. An ergonomically designed hand rail runs all the way around the top of the cart, making it easy to push from any angle. The child seat is safer and more comfortable.

The cart won a 2009 retail design award and was a 2011 finalist for an industrial design award. The carts debuted in 2006 and will be in all Target stores in a few more years, according to Target spokesperson Jessica Carlson.

It's a long way from the late 1930s, when Piggly Wiggly supermarket chain owner Sylvan Goldman was pondering ways to get his customers to buy more. Small baskets were the norm back then. Experimenting with a wooden folding chair, a basket and a set of wheels, the design evolved into a metal frame holding two wire baskets, and was soon mass-produced. But people didn't immediately love the idea. Women thought they looked too much like baby carriages, and men thought they were effeminate. Goldman had to do some hard marketing, hiring greeters to explain the merits of the carts, and models to push them around. By 1940, Goldman had a seven-year waiting list for his new carts.

Next time you slide your cart neatly into its brother at the corral, thank Orla Watson of Kansas City, Mo., who invented the telescoping cart with a hinged opening to nest carts together. The Smithsonian's National Museum of American History in Washington was bequeathed two of the early cart designs, and also has Goldman's original.

David R. Bell, professor of marketing at The Wharton School, agrees that a nice cart enhances the in-store experience. "A clean and easy-to-use cart sends a signal that the store's 'high quality' and this peripheral cue might lead to more buying."

Grocery stores are also sensitive to the "cart factor." Double-basket convenience carts are popular, for quick shops and those with small households. They're popular with thieves, though — ShopRite had several dozen when they opened a new store in New Rochelle, N.Y., and just a few months later, most of them had been pilfered.

Cart theft is a big deal for retailers. With each cart worth $75 to $250, safeguarding a store's supply is important. Some stores in Canada, Europe and Australia have adopted a cart rental system, similar to those found in many airports in the U.S. A coin releases the cart to you, and is returned with the cart. But the system is cumbersome. Anti-theft systems like Systec's SmartStop and Gatekeeper's CartControl use perimeter technology to lock the cart's brakes if there's an attempt to leave the lot, and have proven more effective.

In Shanghai, a company is testing a smart cart that can scan items from a PC tablet embedded in the cart. Bell, the marketing professor, says the cart of the future may do more than that. Say the consumer swipes or keys in a loyalty card number; the cart could then offer shopping tips. But it would have to be smart enough to provide targeted information based on past purchases and a profile.

"Does it recommend great fresh stuff for dinner, or is it trying to sell me cat food when I don't have a pet?" Bell said.