That NAFTA has provided benefits for Mexico and Canada is evident.
Certainly volume of trade has increased sharply since NAFTA was established in 1994. But for the US the trade deficit has also ballooned. Some US jobs have shifted to Mexico. And whether NAFTA has created any real, net benefits for the US economy is more than a little doubtful.
When Donald Trump castigates US industry for shifting jobs to Mexico, he has a point.