Ask the people in the Rust belt how that worked out for them.
Factories moved to other countries along with the 30% of innovation that comes from the shop floor.
The other countries learned about the design and manufacture of the products and competitors spring up.
Back to tariffs: If implemented, all US products have to pay 25% more for the imported goods from Canada & New Mexico or source them elsewhere. Presumably, they're getting them from Canada & Mexico because that is the best quality, price, landed cost (less shipping costs) and shorter lead times, etc. They might find a better price but quality, lead time for delivery, shipping costs, etc have costs too.
There will be major supply chain problems - some won't be able to deliver product.
As their costs go up substantially so their prices must follow. American companies won't be able to export as much because their product prices are that much less competitive. => layoffs
But if they locate outside the US, they will bypass a substantial cost increase. => more layoffs
US imports and exports shrink and the economy gets weaker - strengthening all the other countries.
Trump is nearly as dumb as his supporters.
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