[worst-case scenario]

Actually, illegal immigrants have every reason not to assimilate. If you're living here illegally, the last thing you want is to attract attention in the "legal" community. You're going to stick to the neighborhoods where people speak your language - Spanish, Nahuatl, Maya. (You'll rely on your kids, going to the public school, to translate for you.) You're going to keep on the down-low - don't report that fire-code violation which places the house you and 43 other people are renting, and which will ignite your neighbors' homes when yours burns down. You'll buy a forged drivers' license and not take the driving test. (The rules of the road are the same in every country, right?) There are a lot of costs to America that aren't calculated into this problem.

[hedgetrimmer]

Actually, illegal immigrants have every reason not to assimilate.

You're absolutely right. In fact Vicente Fox calls those in the US "heroes" and welcomes them back every year at Christmas while they take their winter break. You see, they are propping up his corrupt government with $19 billion a year stolen from the American economy. When they are done looting our economy, they now go back to Mexico and collect social security from the American government. The American government has also set up home loan programs funded by the American people, so that when they retire back in their home countries, they can purchase homes at a very low cost. Why should they assimilate?

[beezdotcom]

The only problem with your argument is that it also describes the activities of a number of LEGAL immigrants who don't assimilate - and I'm not against LEGAL immigration (although if you have ideas on encouraging THEIR assimilation, I'm all ears.)