Trading Cards were a very popular source of advertising and selling more, just to complete the collection of cards. Some people would trade cards to try to complete their collection. There are still company's that use this method of sales to captivate buyers today. From Baseball to Tobacco and even in Food Chains, Racing Cards are a big hit too, try to collect all in the series...It is a fun and affordable way of training our kids to be Antique and Collectible people in the future... Someone has to fill the void!