What is your opinion on the North American Union? 
Very good idea.
My guess is that a lot of Americans are worried about the Mexicans.
But when the EU grew, and started to include poor countries like Czech Republic and the Baltic Countries, these nations quickly rose.
On all levels. Their economy experienced incredible growth, and the original countries benefited, in that the total EU market grew bigger, stronger.
A North American Union would allow the countries in it (Mexico, USA, Canada) to get by on the natural resources within. And the NAU market would be big enough that the countries within wouldn't have to export to other countries.
Mexico would rapidly leave the social, economic, and democratic third world status and in a 5-10 year time span be almost on par with the two other countries in NAU.
It would be a solution to the illegal immigrant problem in the southwest of USA as well.
There are discussions about fences to Mexico.
With a NAU, a that fence would definitely be necessary on the south border of Mexico.