wealth originates from growing something, mining something, or manufacturing something.
Mining and growing cannot be moved, so mining and growing are relatively constant wrt trade.
NAFTA moved much manufacturing, one of the three primary sources of wealth, from the USA to Mexico.
So how is NAFTA a benefit to America?
We get cheaper goods and our financial industry profits as well.
It is looking key this - either you learned about the benefits of free trade by studying college level economics or you are doomed to be a protectionist.