The RI Providence Journal has a very clear-headed editorial on illegal immigration: "Costs of immigration":

...Illegal immigration is no free lunch, and it's time we had an honest discussion of the matter...

...Four of America's 10 poorest metropolitan regions lie along the Texas-Mexico border...

...Brownsville, for example, is a stroll across a bridge from Matamoros, Mexico. The population of the once sleepy Texas town grew 41 percent in the 1990s and continues to explode. An amazing 40 percent of the total is under age 19. Imagine a city of only 140,000 trying to support a school system with 40,000 students!

Some 400,000 people live in what are called colonias along the border in Texas. These unincorporated shantytowns often lack water, sewer systems, electricity and paved roads. The colonias residents pay little if any taxes but use the schools and other public services.

Brownsville is the poorest medium-sized American city; a third of its families live in poverty, according to federal guidelines. It's important to recognize that the illegal residents don't just add to the numbers of poor; they also bring down the wages and economic opportunities of the legal residents.

While America's problems caused by illegal immigration are most evident at the Mexican border, the solution lies elsewhere. No number of U.S. Border Patrol jeeps can stop the flow of poor people seeking jobs in the United States. Only penalties for the U.S. employers can do this...