Abstract
This chapter discusses three original data sources used in this book. The first is an opinion survey used to uncover what conspiracy theorists have in common, how they differ from others, and how they think and behave politically, socially, and economically. The second is a sample taken over 121 years of letters to the editor of the New York Times and the Chicago Tribune—more than 100,000 in total. These letters provided not only a consistent public record of conspiracy talk over a century, but also allow researchers to determine the overall level of conspiracy theorizing and which conspiracy theories were most popular at any given time. The third consists of 3,000 articles and posts from Internet blogs and news outlets. Each source has its weaknesses, but the data highlight the information environment and permits informed inquiry into conspiracy theories from the age of yellow journalism to the Internet age.