<P> According to the Economic Policy Institute, California, Texas, Michigan and other states with high concentrations of manufacturing jobs were most affected by job loss due to NAFTA . EPI economist Robert Scott estimates some 682,900 U.S. jobs have been "lost or displaced" as a result of the trade agreement . However, other studies have found that NAFTA only had a modest impact on manufacturing employment, and that automation explains away 87% of the losses in manufacturing jobs . </P> <P> According to University of California, Berkeley professor of economics Brad DeLong, NAFTA had an insignificant impact on US manufacturing . The adverse impact on manufacturing has been way exaggerated in US political discourse according to DeLong, which is something that Harvard economist Dani Rodrik agrees with . </P> <P> According to a study in the Journal of International Economics, NAFTA reduced pollution emitted by the US manufacturing sector: "On average, nearly two - thirds of the reductions in PM and SO emissions from the U.S. manufacturing sector between 1994 and 1998 can be attributed to trade liberalization following NAFTA ." </P> <P> According to the Sierra Club, NAFTA contributed to large - scale, export - oriented farming, which led to the increased use of fossil fuels, pesticides and GMO . NAFTA also contributed to environmentally destructive mining practices in Mexico . It prevented Canada from effectively regulating its tar sands industry, and created new legal avenues for transnational corporations to fight environmental legislation . In some cases, environmental policy was neglected in the wake of trade liberalization; in other cases, NAFTA's measures for investment protection, such as Chapter 11, and measures against non-tariff trade barriers threatened to discourage more vigorous environmental policy . The most serious overall increases in pollution due to NAFTA were found in the base metals sector, the Mexican petroleum sector, and the transportation equipment sector in the United States and Mexico, but not in Canada . </P>

Which of the following is the primary function of the north american free trade agreement (nafta)