ABSTRACT
Nation-states have always been concerned about the security of their borders and who may and may not cross those borders. The land borders of the United States (US) represent its national boundaries with the nations of Mexico and Canada, through which pass many individuals, vehicles, and goods. The sea borders of the US include the myriad of ports through which massive quantities of goods and people enter and depart the nation. The borders of the US represent a line of demarcation that intangibly separates the US from other nations. Many border and transportation security improvements occurred after the tragic events of September 11, 2001. Transportation security involves moving commerce and people safely and quickly. The uses of aviation and aerospace resources have long been associated with the notion of security. Air carriers en route to the United States from a foreign country are required to submit passenger manifests before their arrival at a US port of entry.
