According to a study published in the Journal of International Economics, NAFTA reduced U.S. manufacturing pollution: “On average, nearly two-thirds of U.S. manufacturing reductions in coarse particulate matter (PM10) and sulphur dioxide (SO2) between 1994 and 1998 can be attributed to trade liberalization to NAFTA.”  Since NAFTA, trade between the United States and its North American neighbors has more than tripled and grown faster than U.S. trade with the rest of the world. Canada and Mexico are the top two destinations for U.S. exports, with a share of more than one-third. Most estimates conclude that the agreement has increased U.S. gross domestic product (GDP) by less than 0.5%, which equates to an additional $80 billion over the U.S. economy, with full implementation or several billion dollars of additional growth per year.
Since the first negotiations, agriculture has been a controversial topic within NAFTA, as has been the case with almost all free trade agreements signed under the WTO. Agriculture was the only party that was not subject to trilateral negotiation; Three separate agreements have been signed between the two parties. The Canada-U.S. agreement provided for significant tariff restrictions and quotas for agricultural products (mainly sugar, dairy products and poultry products), while the Mexico-U.S. pact allowed for broader liberalization within a time frame (this was the first North-South free trade agreement for agriculture to be signed). [Clarification needed] It is impossible to isolate the effects of NAFTA in the larger economy. For example, it is difficult to say with certainty what percentage of the current U.S. trade deficit, which reached a record $65,677 million at the end of 2005, is directly attributable to NAFTA. It is also difficult to say what percentage of the 3.3 million manufacturing jobs that were lost in the United States between 1998 and 2004 is the result of NAFTA and what percentage would have been created without this trade agreement.
It cannot even be said with certainty that the intensification of trade between NAFTA countries is exclusively the result of the trade agreement. Those who support the agreement generally claim NAFTA loans for enhanced trade activity and reject the idea that the agreement has resulted in job losses or a growing trade deficit with Canada and Mexico ($8,039 million and $4,263 million respectively in December 2005). Critics of the agreement generally associate it with these deficits and job losses. The North American Free Trade Agreement (NAFTA) was inspired by the success of the European Economic Community (1957-1993) in removing tariffs to stimulate trade among its members. Supporters argued that the creation of a free trade area in North America would bring prosperity through increased trade and production, resulting in the creation of millions of well-paying jobs in all participating countries. Many small U.S. companies under NAFTA depended on exporting their products to Canada or Mexico. According to the U.S. Trade Representative, this trade has supported more than 140,000 small and medium-sized enterprises in the United States. NAFTA contained two important endorsements that concealed concerns that companies would relocate their production and production sites to other participating countries to take advantage of lower wages and worker health and safety legislation. The main provisions of NAFTA required a gradual reduction in tariffs, tariffs and other trade barriers between the three Member States, with some tariffs to be abolished immediately and others over a 15-year period. The agreement guaranteed duty-free access for a wide range of industrial products and goods traded between the signatories.