The North American Free Trade Agreement (NAFTA) was implemented to promote trade between the United States, Canada and Mexico. The agreement, which eliminated most tariffs on trade between the three countries, entered into force on 1 January 1994. Many tariffs, notably on agriculture, textiles and automobiles, were phased out between 1 January 1994 and 1 January 2008. President Donald Trump took office in January 2017, attempted to replace NAFTA with a new agreement, and began negotiations with Canada and Mexico. In September 2018, the United States, Mexico and Canada reached an agreement to replace NAFTA with the Agreement between the United States, Mexico and Canada (USMCA), and the three countries ratified it by March 2020. NAFTA remained in effect until the implementation of the USMCA.  In April 2020, Canada and Mexico informed the United States that they were ready to implement the agreement.  The USMCA entered into force on July 1, 2020, replacing NAFTA. A study published in the August 2008 issue of the American Journal of Agricultural Economics found that NAFTA increased U.S. agricultural exports to Mexico and Canada, even though most of the increase occurred a decade after its ratification. The study focused on the impact that progressive periods of ”phased implementation” of regional trade agreements, including NAFTA, have on trade flows. Most of the increase in Members` agricultural trade, which only recently fell under the jurisdiction of the World Trade Organization, was due to very high barriers to trade prior to NAFTA or other regional trade agreements.
 A fourth round of talks included a U.S. request for a sunset clause that would end the agreement in five years unless the three countries agreed to maintain it, a provision that U.S. Commerce Secretary Wilbur Ross said would allow countries to terminate the agreement if it did not work. Canadian Prime Minister Justin Trudeau met with the House Ways and Means Committee because Congress is expected to pass a bill that would nullify the treaty provisions if Trump tried to withdraw from the pact.  The momentum for a North American free trade area began with U.S. President Ronald Reagan, who incorporated the idea into his 1980 presidential campaign. After the signing of the Canada-U.S. Free Trade Agreement in 1988, U.S.
governments elected President George H. W. Bush, Mexican President Carlos Salinas de Gortari and Canadian Prime Minister Brian Mulroney agreed to negotiate what became NAFTA. Both submitted the agreement for ratification in their respective capitals in December 1992, but NAFTA faced significant opposition in the United States and Canada. The three countries ratified NAFTA in 1993 after the addition of two subsidiary agreements, the North American Agreement on Labour Cooperation (NAALC) and the North American Convention on Environmental Cooperation (NAAEC). The North American Free Trade Agreement (NAFTA; Spanish: Tratado de Libre Comercio de América del Norte, TLCAN; The North American Free Trade Agreement (NAFTA) was an agreement signed by Canada, Mexico and the United States that created a trilateral trading bloc in North America. The agreement entered into force on 1 August. It came into force in 1994 and replaced the 1988 Canada-U.S. Canada-Canada Free Trade Agreement.  The NAFTA trade bloc formed one of the largest trading blocs in the world in terms of gross domestic product. Since the first negotiations, agriculture has been a controversial issue within NAFTA, as has been the case with almost all free trade agreements signed under the WTO.
Agriculture was the only step that was not negotiated trilaterally; Instead, three separate agreements were signed between each pair of parties. .