Matthew Frye Jacobson argues in this text about America's racial odyssey, that race resides not in nature but in the contingencies of politics and culture. In ever-changing racial categories we glimpse the competing theories of history and collective destiny by which power has been organized and contested in the USA. Looking at the field of "whiteness studies" and linking it to traditional historical inquiry, Jacobson shows that in the USA, nation of immigrants, "race" has been at the core of civic assimilation: ethnic minorities in becoming American were reracialized to become Caucasian. He provides a counter-history of how nationality groups such as the Irish or Greeks became Americans as racial groups like Celts or Mediterraneans became Caucasian. Jacobson tracks race as a conception and perception, emphasizing the importance of knowing not only how we label one another but also how we see one another, and how that racialized vision has largely been transformed in the 20th century.