In the first quarter of 2015, the United States became the first importer of cars made in Mexico, according to Mexican automobile association AMIA.
The largest US auto manufacturers have facilities in Mexico. Companies like Mercedes Benz and BMW will start manufacturing there in 2018 and 2019, respectively.
Trump threatens to renegotiate, or directly break, NAFTA, the free trade agreement with Canada and Mexico that, he argues, is hurting US workers.
By that treaty, if at least 65% of parts of a car originate in the United States, then they can be sold duty-free in all three NAFTA countries.
US manufacturers took advantage of that to invest in Mexico. Between 1999 and 2013 foreign investments in Mexico exceeded US $ 30 billion, according to specialized agencies in that country.