Quote History Quoted:
The difference between US and Mexico border and the North and South Korea border is the Korea border stops movement. As far as adopting Mexico or making it a territory we will create a horrible insurgency in our own country. The corruption won't just stop because we step in, recent events testify to that
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And the reason why the Korean border stops movement is that both parties work to make that happen, unlike the US/Mexican border.
I honestly do not think that Mexico would have to be taken by force creating an insurgency, offering the common man everything the US offers I think would swing the popular vote.
Yes it would take years and billions/trillions to develop Mexcio but the end payoff of the resources would make it worth it. The Louisiana purchase and acquisition of Alaska were considered wastes of resources too.
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Also keep in mind that many Mexicans are actually very conservative. Most of the Mexicans here in the US lean liberal simply because of immigration and social service access. If they were brought into the fold then the issues they typically vote on would be gone and they would lean back towards their conservative roots.