Exactly. Plus, a significant percentage of "their" goods are manufactured by US companies. We get a lot of off-season fruits and vegetables, from Mexico (Mexico dominates our fruit and vegetable imports by a wide margin - 69% of vegetable imports and 37% of fruit imports), but we can also get all of that from Argentina, Chile, Peru and Brazil (and Canada), or simply grow most of it here in the Rio Grande Valley and in the San Joaquin Valley in California (assuming California will trade with the US). It's mostly avocados and tomatoes. California alone could easily absorb the extra demand for avocados, since they have more than 1/3 of their Valley farm acreage vacant for experimentation and for ramping up production if needed. And the tomatoes can be grown in Texas and Arizona, or in a hothouse (I abhor hothouse tomatoes, though).
A couple or three days ago CNN's Money had a really snarky article called Here's What Else We Import from Mexico, Mr Trump. Top of the list was $21.5 billion worth of motor vehicles, 8% of our imports from Mexico. Next was the $51.6 billion in auto parts e import, 19% of Mexican imports. But they didn't stop there. Mexico is our third largest supplier of goods overall, so there. We also import computer monitors, insulated wire and electric generators. And, and, and, major appliances like refrigerators, air conditioners and centrifuges.
The thing is, every one of those things on that list are imported from Mexico solely because American companies moved their manufacturing to Mexico. Mexico on their own doesn't make any of that stuff. Zero.
As a footnote, the state that 40% of the parts in a typical Mexican product originated in the US. They don't really mention that if manufacturing and assembly were moved back here, those 40% would never be exported to Mexico in the first place, except as finished products to be sold.
In the long run, the only thing a trade war or a stiff tariff would really hurt the US on is with Corona. Modelo Especial. and Dos Equis beer, and Cholula hot sauce. <snort>