Well, what do you want? Do you want cheap labor, or do you want sound borders? Illegal immigration has been an economic boon to the US, providing between 10 and 20 million workers that have moderated the costs of construction, housekeeping, daycare, food service, and agriculture even while oil and other commodity prices are pushing inflation up.
Illegal immigrants have increased the US workforce by 5-10% in recent years, and have been a key factor in recent economic growth. The price: some displacement of poor American workers, growing Latin-American influence on US culture, and insecure borders. Economists are having a hard time measuring American job loss to illegals, chiefly since growth has provided other opportunities (they also find it difficult to measure any net loss in tax collections or state benefits). And while the Mexican border may be insecure, the Canadian border is the only border previously used by anti-American terrorists.
The only price paid so far, then, is the increasing Latinization of American culture.
Politicians on the social right are pandering to some Americans’ xenophobic fear of cultural dilution with the onslaught of immigrants. If you view cultural diversity as a threat, then for you the fear and costs are real. While the border should be secure both on principle and so that the US can create a rational immigration policy, the benefits of illegal immigration have so far outweighed the costs. And guess what: that’s exactly why it’s been allowed to go on for so long.