there have been long term plans in place in regards to the "free trade" region of US/Canada/Mexico which includes addressing issues of immigration, etc. a militarized border has been pointed out as one of the bulletpoints by the cfr and other gatherings of the military/corporate guys.

immigrants are also easy targets in a time of economic depression, while - as you pointed out - the root causes that effects workers in the us competing against slave labor wages and the reasons for illegal immigration in the first place are "off the table."