Before sending it to the U.S. Senate, Clinton added two subsidiary agreements, the North American Agreement on Labor Cooperation (NAALC) and the North American Agreement on Environmental Cooperation (NAAEC) to protect workers and the environment, as well as to allay the concerns of many members of the House of Representatives. The United States has required its partners to comply with similar environmental practices and regulations. [Citation required] After much attention and discussion, the U.S. House of Representatives passed the North American Free Trade Agreement Implementation Act on November 17, 1993. Supporters of the deal included 132 Republicans and 102 Democrats. The legislation passed the Senate on November 20, 1993, 61-38.  The Supporters of the Senate were 34 Republicans and 27 Democrats. Republican Congressman David Dreier of California, a staunch supporter of NAFTA since the Reagan administration, has played a leading role in mobilizing support for the agreement among Republicans in Congress and across the country.   The USMCA is expected to have very little impact on the economy.  An International Monetary Fund (IMF) discussion paper published at the end of March 2019 stated that the agreement would have a “negligible” impact on the general economy.   The IMF study predicted that the USMCA “would have a negative impact on trade in the automotive, textile and clothing sectors, while achieving modest welfare gains, mainly due to improved access to the goods market, with a negligible impact on real GDP.”  The IMF study found that the economic benefits of the USMCA would be significantly increased, whether Trump`s trade war ended (i.e. when the United States lowered tariffs on steel and aluminum imports from Canada and Mexico and Canada and Mexico lowered retaliatory duties on imports from the United States)  In addition to the NAFTA-of-origin provisions , USMCA borrows significant credits from the Trans-Pacific Partnership (TPP) trade agreements and the Comprehensive and Progressive Agreement for the Trans-Pacific Partnership (CPP).
On April 3, 2020, Mexico announced its willingness to implement the agreement and joined Canada.  The agreement came into force on July 1, 2020.     An October 2017 article in The Globe and Mail in Toronto questioned whether the United States wanted to renegotiate the agreement or planned to divest regardless of it, noting that the newly appointed U.S. Ambassador, Kelly Knight Craft, is married to the owner of Alliance Resource Partners, a major U.S. coal operation. Canada is implementing a carbon plan, and it is also about selling bomber jets. “Americans used so many poison pills in last week`s conversations in Washington that they should have been charged with murder,” columnist John Ibbitson wrote.  The United States, Mexico and Canada have reached an agreement to modernize NAFTA, which is 25 years old, into a high-level agreement of the 21st century. The new agreement between the United States and Mexico-Canada (USMCA) will support mutually beneficial trade, which will lead to freer markets, fairer trade and robust economic growth in North America. According to a 2018 Sierra Club report, Canada`s NAFTA and Paris Agreement commitments have been met. The Paris commitments were voluntary and NAFTA was mandatory.
 During the 2016 U.S. presidential election, Donald Trump`s campaign included a promise to renegotiate or eliminate NAFTA if the renegotiations fail.  After the election, Trump made a series of changes that influenced trade relations with other countries.