By telling how the US census classified and divided Americans by race and origin from the founding of the United States to World War II, this book shows how public statistics have been used to create an unequal representation of the nation. From the beginning, the census was a political undertaking, torn between the conflicting demands of the state, political actors, social scientists, businesses, and interest groups. Through the extensive archives of the Bureau of the Census, it traces the interactions that led to the adoption or rejection of changes in the ways different Americans were classified, as well as the changing meaning of seemingly stable categories over time. Census workers and directors by necessity constantly interpreted official categories in the field and in the offices. The difficulties they encountered, the mobilization and resistance of actors, the negotiations with the census, all tell a social history of the relation of the state to the population. Focusing in detail on slaves and their descendants, on racialized groups, and on immigrants, as well as on the troubled imposition of US racial categories upon the population of newly acquired territories, the book demonstrates that census-taking in the United States has been at its core a political undertaking shaped by racial ideologies that reflect its violent history of colonization, enslavement, segregation, and discrimination.