Nineteenth- and twentieth-century race relations are explored through an assimilationist lens, beginning with Robert Ezra Park's understanding of the race relations cycle. The chapter covers African American/white relations from the Reconstruction era to Jim Crow, the shifting racial ideologies that accompany this change, and an exploration of lynching and race riots through the power-threat hypothesis. Additionally, the blocked assimilation of Chinese immigrants, hostility to Irish immigrants, and anti-Semitism in the United States are explored. Finally, in the face of white expansion into western territories, this chapter covers the construction of Native Americans as “problems” and the creation of reservations and boarding schools as “solutions.”