Rachel St. John is an associate professor of History at the University of California, Davis, where she joined the faculty this summer. She teaches courses in US history, environmental history, and transnational borderlands history. A California native, she received her BA and PhD from Stanford University and has been on the faculty at New York University and Harvard University. St. John’s research focuses on nineteenth and twentieth-century North American history with a particular emphasis on state formation, nation building, and national space. Her first book, Line in the Sand: A History of the Western US-Mexico Border was published by Princeton University Press in 2011. She is currently at work on a new book, The Imagined States of America: The Unmanifest History of Nineteenth-century North America, which explores the histories of the many nation-building projects that developed across the continent over the course of the nineteenth century.