How did american methods of selling goods change at the turn of the 20th century?

Goods were advertised and sold in mail-order catalogs, newspapers, magazines, railroad signs, bill boards, and shopping centers are the american methods of selling goods change at the turn of the 20th century. Supposedly around the turn of the century, Marshall Fields department store in Chicago got the bright idea of using its numerous large store windows to diplay goods available for sale. The results quickly grew into the modern era of advertising and consumerism.