Costco's membership retention rate is the stuff of other retailers' dreams, nevermind the love they get on social media. With very little paid advertising, the company has managed to keep its spot as the third largest retailer in the U.S. We’re finding out how they do it with Susan and David Schwartz, authors of “The Joy of Costco: a Treasure Hunt from A to Z,” and Business Insider reporter Dominick Reuter. See Privacy Policy at https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info.