You seem to be a law abiding citizen and would support all the laws and treaties created in your name by our fellow citizens and law makers, Right? Of course you do... I can tell...
How about the Mexican 'Illegal' are just visiting their property pursuant to Article 8 of the Treaty of Guadalupe Hidalgo (1848)?
http://avalon.law.yale.edu/19th_century/guadhida.asp#art8
"Mexicans now established in territories previously belonging to Mexico, and which remain for the future within the limits of the United States, as defined by the present treaty, shall be free to continue where they now reside, or to remove at any time to the Mexican Republic, retaining the property which they possess in the said territories, or disposing thereof, and removing the proceeds wherever they please, without their being subjected, on this account, to any contribution, tax, or charge whatever.
Those who shall prefer to remain in the said territories may either retain the title and rights of Mexican citizens, or acquire those of citizens of the United States. But they shall be under the obligation to make their election within one year from the date of the exchange of ratifications of this treaty; and those who shall remain in the said territories after the expiration of that year, without having declared their intention to retain the character of Mexicans, shall be considered to have elected to become citizens of the United States.
In the said territories, property of every kind, now belonging to Mexicans not established there, shall be inviolably respected. The present owners, the heirs of these, and all Mexicans who may hereafter acquire said property by contract, shall enjoy with respect to it guarantees equally ample as if the same belonged to citizens of the United States."
Imagine 2m Mexicans having an undivided interest in their ancestor's property now passed to them and their cousins and sisters and aunts as rightful heirs..... You'd welcome them... wouldn't you?