In 1885, following the massacre of Chinese miners in Wyoming territory, communities throughout California and the Pacific Northwest harassed, assaulted, and expelled thousands of Chinese immigrants. The Chinese Must Go shows how American immigration policies incited this violence, and how this gave rise to the concept of the "alien" in America. Our story begins in the 1850s, before federal border control established strict divisions between citizens and aliens-and long before Congress passed the Chinese Restriction Act, the nation's first attempt to bar immigration based on race and class. When this unprecedented experiment failed to slow Chinese migration, armed vigilante groups took the matter into their own hands. Fearing the spread of mob violence, policymakers redoubled their efforts to seal the borders, overhauling immigration law and transforming America's relationship with China in the process. By tracing the idea of the alien back to this violent era, Lew-Williams offers a troubling new origin story of today's racialized border.