“Originally, we distributed the Fearless Flyer only in the stores and to a small but growing subscriber list. Doing a mailing to individual addresses, however, was a rotten chore: Americans move about every three years. In 1980, I attended a marketing lecture that taught me that, when someone moves, someone just like them is likely to occupy the same address. This proved to be correct. By mailing to addresses rather than to individuals—by blanketing entire ZIP codes—we were able to tremendously expand the distribution of the Fearless Flyer. The ZIPs to which we mailed, of course, were chosen on the basis of the likely concentration of overeducated and underpaid people.”