The North American Free Trade Agreement (NAFTA) is a treaty of the United States, Canada and Mexico. it came into force on 1 January 1994. (Since 1989, there has been free trade between the United States and Canada; NAFTA has extended this regime.) On that day, the three countries became the largest free market in the world – the combined economies of the three nations were $6 trillion and directly affected more than 365 million people. NAFTA was created to remove customs barriers for agriculture, manufacturing and services; Eliminating restrictions on investment protection of intellectual property rights. This should be done while respecting environmental and labour concerns (although many observers point to the fact that the three governments have been negligent in environmental and safety at work since the agreement came into force). Small businesses were among those expected to benefit the most from the removal of trade barriers, as this would reduce trade activity in Mexico and Canada and reduce the administrative burden associated with importing or exporting goods. Although NAFTA has not kept all its promises, it has remained in place. Indeed, in 2004, the Central American Free Trade Agreement (CAFTA) extended NAFTA to five Central American countries (El Salvador, Guatemala, Honduras, Costa Rica and Nicaragua). In the same year, the Dominican Republic joined the group in signing a free trade agreement with the United States, followed by Colombia in 2006, Peru in 2007 and Panama in 2011. The Trans-Pacific Partnership (TPP), signed on October 5, 2015, represented an extension of NAFTA to a much larger extent.
Economists generally agreed that the U.S. economy as a whole benefited from NAFTA by increasing trade.   In a 2012 survey by the Global Markets Initiative`s panel of economic experts, 95% of participants said that U.S. citizens benefited on average from NAFTA, while no one said that NAFTA was detrimental to U.S. citizens on average.  A review of the 2001 Journal of Economic Perspectives showed that NAFTA was a net benefit to the United States.  A 2015 study showed that welfare in the United States increased by 0.08% and intra-block trade in the United States by 41% due to NAFTA tariff reductions.  It is impossible to isolate the effects of NAFTA on the broader economy.
It is difficult, for example, to say with certainty what percentage of the current United States.