This chapter analyzes the competing racial geographies of the United States and Mexico in the newly annexed territory. Mexican Americans challenged Jim Crow segregation in the Southwest through naturalization, segregation, and discrimination cases brought between 1897 and 1954. The mestizo character of plaintiffs flummoxed the racial geography of the United States in the courts, as the plantiffs' mestizaje was illegible from the perspective of a biracial organization of the American polity. Court decisions repeatedly required Mexicans to renounce their indigenous and African heritage to enjoy the privileges of whiteness, while Mexican-Americans' repeatedly claimed a whiteness that resembles mestizaje. The chapter...