In this richly insightful survey that represents the culmination of decades of research, a leading western specialist argues that the unique history of the American West did not end in the year 1900, as is commonly assumed, but was shaped as much—if not more—by events and innovations in the twentieth century. Earl Pomeroy gathers copious information on economic, political, social, intellectual, and business issues, thoughtfully evaluates it, and draws a new and more nuanced portrait of the West than has ever been depicted before. Pomeroy mines extensive published and unpublished sources to show how the post–1900 West charted a path that was influenced by, but separate from, the rest of the country and the world. He deals not only with the West’s transition from an agricultural to an urban region but also with the important contributions of minority racial and ethnic groups and women in that transformation. Pomeroy describes a modern West—increasingly urban, transnational, and multicultural—that has overcome much of the isolation that challenged it at an earlier time. His final book is nothing short of the definitive source on that West.