In case you were unaware of this, during the Great Famine, hundreds of thousands of Irish came to the United States, to work, and sent the better part of their money home to their families to help pay the rent on their tenant farms, and to pay for food and for passage over to America.

This did not result in a weakening of the United States, though the Irish did change the political, social and religious structures of the places where they lived.

If you are concerned that the Mexicans are going to "take over" the American Southwest, this would be a reason to offer Mexican immigrants an easier citizenship path. If they are citizens, they will have more reason to assimilate, not less. This is especially true because their country of origin has mismanaged its economic system so severely that they were forced to seek employment in a country some of whose citizens speak about them as you do. Why would they want to make their "new" country subject to the poor government and killing economics of the "old" one?

This need not result in a weakening of the United States, though the Mexicans will change the political, social and religious structures of the places where they live.

America, the place and the concept, has been about opportunity, in our folklore and in the popular imagination. In truth, America is about change, which is where opportunity comes from and where opportunity leads. If we abandon change because we don't like its complexion or its vocabulary, we abandon change. We will cease to be who we are and cease to live up to our press releases. This will result in a weakening of the United States, because the "America" part will have been left in the dust of our fear of change.