In the wake of the North American Free Trade Agreement (NAFTA), considerable attention is being paid today to the social, economic, and political landscape of North America. With the rapid growth of north-south commerce, information transfers, capital flows, human migrations, and environmental networks, the process of continental integration is accelerating. Associated with this process is increased permeability of national boundaries -- what Ivo Duchacek has called perforated sovereignties (1988). Transnational contacts and interactions have called into question the traditional national sovereignty function of borders, stirring controversy about new relationships and forms of association that transcend national frontiers.