In my neck of the woods, illegal immigration from points south of the border can be a much discussed topic. Congress tried to tackle immigration recently, and failed miserably. So here's my plan to solve it once and for all.
Now don't freak out. I'm not saying "Mexifornia" is going to take over the rest of the country, nor am I arguing that you give up English or Americanism or any other such thing.
The "problem", as I see it, with illegal, southern immigration is that a second culture, a second country really, has and is being formed. When I go to the grocery store, I watch people. I watch as English speakers and Spanish speakers self-segregate. They don't speak to each other, they hardly look at each other. There may be a furtive smile, or a nod of the head as they pass in the aisle, but no more open communication than that occurs. And that's stupid.
I speak Spanish. When a native Spanish speaker finds out that I speak, their entire countenance changes. They smile. They move a little closer and ask me how I learned. I can sense as they gauge how fast they can speak and still have me understand. I love seeing the question in their face as they realize I am speaking a form of Spanish called Castellano, where the "y" and the "ll" make a "sh" sound. Generally they will compliment me on how I speak, but mostly just that I speak. An instant bond is formed.
That bond comes about because of our common language. This is the bond that lessens the impact of that "second country". It does away with the furtive smiles and nods of the head. It is the bond that creates a community.