This book examines the politics of the United States' westward expansion, showing how the government's regulation of population movements on the frontier, both settlement and removal, advanced national aspirations for empire and promoted the formation of a white settler nation. The book details how a government that struggled to exercise plenary power used federal land policies to assert authority over the direction of expansion by engineering the pace and patterns of settlement and to control the movement of populations. At times, the government mobilized populations for compact settlement in strategically important areas of the frontier; at other times, policies were designed to actively restrain settler populations in order to prevent violence, international conflict, and breakaway states. The book examines how these settlement patterns helped construct a dominant racial vision for America by incentivizing and directing the movement of white European settlers onto indigenous and diversely populated lands. The book pays close attention to the failures as well, from the lack of further expansion into Latin America to the defeat of the black colonization movement. It reveals the lasting and profound significance government settlement policies had for the nation, both for establishing America as dominantly white and for restricting broader aspirations for empire in lands that could not be so racially engineered.