but what about the average American?
Also better off.
Each country (US, Canada, Mexico) has some strength and some weakness. In the U.S. we have lots of capital and managerial experience. We have a good system of laws and financial transparancy. We do not have a good labor supply and are so-so on raw materials.
Canada has raw materials but a statist government and fewer qualified citizens. They also dont have much ready labor.
Mexico has some raw materials (oil), not much middle class, little access to capital, and a lot of cheap labor. They also have huge corruption problems and monopoly issues. The richest man in the hemisphere, Carlos Slim, largely profited from gov't monopoly.
Take the best of all of them and you will build a much richer society.