In a dissertation, or any research subject for that matter, there are generally both narrow and broader queries that can be pursued on a given theme. The narrow theme in this case concerns the "motives for French railroad-building in Senegal." Unfortunately, despite prolonged searches through archival sources available in Senegal, it soon became obvious that there were simply too many missing particulars to be able to complete this story well. Even while searching out the missing information gaps for the narrow theme, however, it also proved possible to gather abundant material for the broader theme of the social impact of the railroad in Senegal, on trade patterns, on labor, and on land— sufficient material at the end of a two-year sojourn in Senegal to write a dissertation regardless of the missing gaps in the narrow theme.