"On January 1, 1994, the North American Free Trade Agreement (NAFTA) between the United States, Canada, and Mexico entered into effect. NAFTA, the most comprehensive free trade agreement ever negotiated, is expected to create the world’s largest free trade zone when it is gradually implemented over the next decade. Since NAFTA was such a controversial treaty, the three countries agreed to adopt NAFTA-related accords in order to address concerns about environment, labor, and border area development." (Quoted from paper)