Today, Americans are buying more imported merchandise than ever
before, and more of the goods produced in U.S. factories are
bound for export. Much of the imported merchandise is
transported in containers from far-flung corners of the world,
raising the need for heightened cargo security measures from the
foreign points of origin to the final destinations in the United
States. In 2001, the U.S. transportation system carried
merchandise exports worth $731 billion and merchandise imports
valued at $1.1 trillion (in current dollars). Transporting this
merchandise requires a significant amount of equipment. For
example, in 2001, there were over 936,000 aircraft, 215,000
maritime vessels, and 19 million vessel, truck, and rail
container entries into the United States.1 From a national
security perspective, the large amount of transportation
equipment involved in U.S. international trade highlights the
possible threat of using freight vessels and vehicles for
terrorist activity. This vulnerability underscores the i