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.“  A Chapter 19 panel should consider whether the Agency`s decision was supported by „substantial evidence.“ This standard was a considerable tribute to the national agency. Some of the most contentious trade disputes in recent years, such as the U.S.-Canada dispute over conifers, were negotiated ahead of chapter 19 panels. 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] After diplomatic negotiations in 1990, the heads of state and government of the three nations signed the agreement on 17 December 1992 in their respective capitals.  The signed agreement had to be ratified by each country`s legislative or parliamentary department. On September 30, 2018, the deadline for negotiations between Canada and the United States, an interim agreement was reached between the two countries, thus retaining the trilateral pact when the Trump administration submits the agreement to Congress.
 The new name of the agreement was the United States-Mexico-Canada Agreement (USMCA) and came into force on July 1, 2020.   The adoption of NAFTA has resulted in the removal or removal of barriers to trade and investment between the United States, Canada and Mexico. The impact of the agreement on issues such as employment, the environment and economic growth has been the subject of political controversy. Most economic analyses have shown that NAFTA has been beneficial to North American economies and the average citizen, but has been detrimental to a small minority of workers in sectors subject to trade competition.   Economists have estimated that the withdrawal from NAFTA or the renegotiation of NAFTA, in a way that would have created restored trade barriers, would have affected the U.S. economy and cost jobs.    However, Mexico would have been much more affected, both in the short term and in the long term, by the loss of jobs and the reduction of economic growth.  According to a 2017 report by the New York City public public tank report, Council on Foreign Relations (CFR), bilateral trade in agricultural products tripled between 1994 and 2017 and is considered one of the main economic effects of NAFTA on trade between the United States and Canada, with Canada becoming the largest importer of the U.S.
agricultural sector.  Fears of job losses in the U.S. manufacturing sector were not due to the fact that manufacturing employment remained „stable“. Given Canada`s labour productivity, which rose to 72% of the U.S. level, hopes of closing the „productivity gap“ between the two countries were also not realized.  The North American Free Trade Agreement (NAFTA) is an international agreement signed by the governments of Canada, Mexico and the United States, which has created a trilateral trade bloc in North America.