Where can one go to find datasets relevant to historical research? As far as ferreting out data goes, this is one area where historians have made a real contribution to quantitative studies in the social sciences. For it is historians who have mined the many and varied sources of quantitative data from the prestatistical age, and it is mostly historians who have found and used published sources of social and economic data from the period before 1900. As far as published data goes, the first place you should look is your library's social science data collection. Many universities are part of the University of Michigan consortium, which means that virtually all of the social science datasets that are publicly available can be downloaded in your library without too much trouble. That includes all sorts of exotic things that you wouldn't think of as having a historical element. For example, I know that the Roper collection is available for public opinion surveys going back to the 1930s. Enormous amounts of historical data are likewise available on the Internet. I myself, for instance, placed a large amount of data on the Atlantic slave trade that is available online from the University of Wisconsin. We also have, as I mentioned in Chapter 6, IPUMS, the public use sample of the U.S. census from 1850 to 2000. Using these materials, the historian can do time depth studies and observe how a certain variable changes over time.