Borders cut through not just places but also relationships, politics, economics, and cultures. Eric V. Meeks examines how ethno-racial categories and identities such as Indian, Mexican, and Anglo crystallized in Arizona's borderlands between 1880 and 1980. South-central Arizona is home to many ethnic groups, including Mexican Americans, Mexican immigrants, and semi-Hispanicized indigenous groups such as Yaquis and Tohono O'odham. Kinship and cultural ties between these diverse groups were altered and ethnic boundaries were deepened by the influx of Euro-Americans, the development of an industrial economy, and incorporation in the U.S. nation-state. Old ethnic and interethnic ties changed and became more difficult to sustain when Euro-Americans arrived in the region and imposed ideologies and government policies that constructed starker racial boundaries. As Arizona began to take its place in the national economy of the United States, primarily through mining and industrial agriculture, ethnic Mexican and Native American communities struggled to define their own identities. They sometimes stressed their status as the region's original inhabitants, sometimes as workers, sometimes as U.S. citizens, and sometimes as members of their own separate nations. In the process, they often challenged the racial order imposed on them by the dominant class. Appealing to broad audiences, this book links the construction of racial categories and ethnic identities to the larger process of nation-state building along the U.S.-Mexico border, and illustrates how racial differences can both fuse cultures together and drive them apart.