In summer 2014, US agencies responsible for the border with Mexico were overwhelmed by tens of thousands of unaccompanied children arriving from Central America. Unprepared to address this unexpected kind of migrant, the US government deployed troops to carry out a new border mission: the feeding, care, and housing of this wave of children. This event highlights the complex social, economic, and political issues that arise along borders. In American Crossings, nine scholars consider the complicated modern history of borders in the Western Hemisphere, examining borders as geopolitical boundaries, key locations for internal security, spaces for international trade, and areas where national and community identities are defined. Among the provocative questions raised are, Why are Peru and Chile inclined to legalize territory disputes through the International Court of Justice, undermining their militaries? Why has economic integration in the "Tri-Border Area" of Argentina, Brazil, and Paraguay increased illicit trade supporting transnational terrorist groups? And how has a weak Ecuadorian presence at the Ecuador-Colombia border encouraged Colombian guerrillas to enforce the international borderline?

This is the first book-length study of why states sometimes ignore, oppose, or undermine elements of the nuclear nonproliferation regime-even as they formally support it. Anchored by the Treaty on the Non-Proliferation of Nuclear Weapons, the nuclear nonproliferation regime is the constellation of agreements, initiatives, and norms that work in concert to regulate nuclear material and technology. The essays gathered here show that attitudes on nonproliferation depend on a ""complex, contingent decision calculus,"" as states continually gauge how their actions within the regime will affect trade, regional standing, and other interests vital to any nation. The first four essays take theoretical approaches to such topics as a framework for understanding challenges to collective action; clandestine proliferation under the Bush and Obama administrations and its impact on regime legitimacy; threat construction as a lens through which to view resistance to nonproliferation measures; and the debate over the relationship between nuclear disarmament and nonproliferation. Essays comprising the second part of the book use regional and state-specific case studies to look at how U.S. security guarantees affect the willingness of states to support the regime; question the perceived spoiler role of a ""vocal minority"" within the Non-Aligned Movement; challenge notions that Russia is using the regime to build a coalition hostile to the United States; contrast nonproliferation strategies among Latin American countries; and explain the lag in adoption of an Additional Protocol by some Middle East and North African countries. Getting countries to cooperate on nonproliferation efforts is an ongoing challenge. These essays show that success must be measured not only by how many states join the effort but also by how they participate once they join.