The North America Free Trade Agreement (NAFTA) of 1994 created a unified market of more than 370 million people with goods and services totaling $6.5 trillion annually. The elimination of tariffs was scheduled to occur over a 15-year period, though most were eliminated in the first five years. In 1994, the free-trade area was second only to the European Union in terms of value of goods and services. After heated debate, especially in the United States and Canada, NAFTA was signed by the presidents of the United States, Mexico, and Canada on December 17, 1992. Advocates of the agreement argued that the total number of jobs would increase in all three countries and that the free movement of goods and services would result in lower costs. They also suggested that the creation of more and better jobs in Mexico would lessen the undocumented immigration into the United States. Many environmental and labor groups in the United States and Canada vigorously opposed the treaty, fearing the loss of well-paid jobs to Mexico and degradation of the environment as companies moved south. The measure was ratified by the legislatures of all three countries in 1993 and took effect on January 1, 1994. Under North American Free Trade Agreement provisions, temporary admission restrictions were eased on business visitors, professionals, intracompany transferees, and traders and investors moving between countries. Cross-border truck traffic was also liberalized, although it was again tightened following the terrorist attacks of September 11, 2001, and continued to be examined in light of several 2003 incidents involving the deaths of illegal Mexican immigrants being smuggled into the United States in trucks.