Trump's expertise and knowledge is in real estate, not in bringing back manufacting and industrial jobs. Those companies started jumping ship as soon as NAFTA was signed into law by President Clinton on December 8, 1993, and took effect on January 1, 1994.

Under NAFTA, the United States, Canada, and Mexico become a single, giant, integrated market of almost 400 million people with $6.5 trillion worth of goods and services annually.

This year, major American companies, like Ford, started moving small-car manufacturing to Mexico. Likewise, United Technologies, Cardone and Dematic announced recently they will move plants to Mexico, cutting 3700 U.S. jobs.

CNN reported in March, 2016, that since the year 2000, the US lost five million manufacturing jobs to Mexico. Fiat Chrysler said in July, 2016, that within a year the company will stop most all manufacturing in the US, and will possibly move its operations to Mexico, reports USA Today.

For decades, U.S. automakers outsourced jobs to Mexico because of its comparative advantage in cheap and abundant labor. However, because most blue-collar Americans don't want to move to Mexico to work there, the factories are investing in robotic workers instead. (Source)