In 1937 Sylvan N. Goldman introduced the first shopping cart into his Oklahoma City Piggly-Wiggly Grocery store.  He noticed that his patrons stopped their shopping when their hand baskets became too heavy to carry.  He realized that physical strength was limiting the ability of man to shop.  Goldman's idea was initially not successful but with time, some shills, and modifications, his invention made him a multimillionaire.

Today the major retailers in America who do not use shopping carts in their business are falling behind while those who make their use part of their business plans are successful.  Compare Sears and JC Penny to Wal-Mart.