By transporting waves of newly arrived immigrants along rail lines from both coasts, railway companies played an active role in repopulating the interior of the country. Spaces of Immigration follows the travel routes of immigrants during this foundational period of American infrastructure—from ports of arrival to train cars and depots to settlements—showing how the built environment of the railways fostered segregation through physical isolation and reinforced hierarchies according to race, ethnicity, and class. Catherine Boland Erkkila highlights the magnitude of this forced separation: how spatial design and the experiences within it reflected prejudices of contemporary middle-class Americans who viewed immigrants as poor, diseased, and dangerous. Spaces of Immigration draws attention to the control wielded by railroad companies and government officials, who dispatched European immigrants to ethnic enclaves across the Midwest, some of which still exist. These colonization efforts, Boland Erkkila argues, were motivated by profit through exploitation: the promise of cheap labor and the purchase of land along designated routes. At the same time, Asian immigrants were detained like prisoners on the West Coast. This book ultimately offers a greater understanding of the immigrant experience in America through the lens of spatial history, revealing deeply embedded conflicts still pervasive in our society today.