To answer the question of the original poster - Canada/USA/Mexico are already very interconnected economically via NAFTA. What this new legislation is attempting to do is create a North American Exclusive Economic Zone - how that differs from NAFTA, I have no idea.
The conspiracy theorists will have you believe this is an evil secret done in order to erase America's borders. In actuality, its simply an economic move that is designed to compliment NAFTA. (As far as I know). We aren't really merging the three countries together - rather just strengthening the economic relationships that exist between the three.
