The naturalist Alexander von Humboldt, visiting the Gulf-Caribbean in the early nineteenth century, called it America’s Mediterranean. Almost a century later, Southern California was hailed as “Our Mediterranean, Our Italy!” Although “American Mediterranean” is not a household phrase in the United States today, it once circulated widely in French, Spanish, and English as a term of art and folk idiom. In this book, Susan Gillman asks what cultural work is done by this kind of unsystematic, open-ended comparative thinking. tracks two centuries of this geohistorical concept, from Humboldt in the early 1800s, to writers of the 1890s reflecting on the Pacific world of the California coast, to writers of the 1930s and 40s speculating on the political past and future of the Caribbean. Following the term through its travels across disciplines and borders, reveals a little-known racialized history, one that paradoxically appealed to a range of race-neutral ideas and ideals.