The terrorist attacks on the World Trade Center and the Pentagon on September 11, 2001, brought the issue of U.S. border security to the forefront. In the weeks following the attacks, heightened U.S. security measures caused serious delays on the northern and, especially, the southern borders. Increased security will increase the cost of business in the NAFTA countries. Resources must be deployed in a way that minimizes the economic costs of doing business across the borders of an increasingly integrated North American economy. At the same time, this must be accomplished without compromising U.S. security needs. Therein lies the dilemma.