For assistance of many varieties, I thank the following librarians and archivists: Susan Snyder, Erica Nordmeier, and the entire staff at the Bancroft Library at the University of California, Berkeley; Kim Walters and Liza Posas at the Braun Research Library at the Southwest Museum of the American Indian/Autry National Center in Los Angeles; Romaine Ahlstrom at the Huntington Library in San Marino, California; and John Mark Lambertson at the National Frontier Trails Museum in Independence, Missouri.
Experts in various components of the story provided assistance. Several are thanked in the notes, but my particular gratitude to Mark McLaughlin for his help in understanding Sierra Nevada weather and to Penny Rucks for helping me to understand the history of the Washoe Indians, especially their oral traditions regarding the Donner Party.
My agent, Deirdre Mullane at The Spieler Agency, was a constant source of support and assistance from proposal to final manuscript. At Oxford University Press, Cybele Tom edited the book with a sure hand. Among others at Oxford, I thank Furaha Norton, who acquired the project, production editor Joellyn Ausanka, and copy editor India Cooper, whose fine reading saved me many an error or sloppy sentence.
On a more personal level, thanks for various reasons to Dan Borenstein, Yvonne Condes, Sonia Krishnan, Mike Lewis, Anthony Love-day, and Ellen Quain, as also to my brother and his family—Jeff, Patty, Micah, and Carl Rarick. Last, my thanks to two remarkable women: My daughter, Ellie, is a joy and inspiration, while Allison Ellman provided constant love and support, not to mention great patience when I was absorbed with the countless tasks of book writing.