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.
True Cost - Analyzing our economy, government policy, and society through the lens of cost-benefit 
In my opinion, cultural dilution is a real problem, but honestly, I don’t think the American culture is being so much diluted as it is being transformed. I’ll state the age old argument here “America was built by immigrants”. It’s old but just as true as it’s always been. Over the years as immigrants arrived they have brought new aspects of their culture with them, some more accepted than others. For example, at one time the polish, Russian, and Italian people were considered too strange to ever fully assimilate into American culture. Obviously now we’re aware the were completely able to do this. We’re going through the same thing now, just with different immigrants.
I can also however see why this situation worries people. It can undoubtedly be unnerving to feel like your lifestyle is being threatened, maybe the natural response is to reject it. Some feel that by allowing immigrants, illegal or otherwise, into the country, we are sacrificing some of our culture to accommodate them. Not everyone is thrilled to have immigrants bring their way of life over, isn’t the point of immigration to attempt to assimilate into this country’s culture?
Another viewpoint on this is immigrants breathe new life into our country in a way that keeps it young and growing. It seems with every generation we’re growing to accommodate a new plethora of nationalities into our country. The ‘Immigrant of the moment’ right now, so to speak, would be primarily Mexicans. With them they bring many aspects of their culture. Some see this as a good thing, and others view this as a very unpleasant thing that’s happening.
For most people I don’t believe it’s immigrants they have problems with. I’ll repeat myself, “America was built on immigrants”, but it’s the methods some people use in coming here that turns people off to it. I believe a good amount of people don’t have any problem with immigrants, but they do have a problem with illegal immigrants. When people immigrate illegally to the US they rarely have an intention of assimilating, very rarely have a grasp of the language, and are less likely to try and add productively to the society.
Many believe there are procedures in place for a reason, we don’t try to keep certain people out for fun, it’s not a hobby of ours to decide who comes here. There are factual grounds to the reasons why the people who are let in are let in. With all the legal opportunities to immigrate in place, when people go through illegal means it doesn’t sit well with the original inhabitants of the country, nor with the people who actually went through the process of coming here legally.
The change has to happen, but it has to be gradual. Work on securing the borders. It won’t happen overnight anyway. Reduce the tide of incoming illegal immigrants. Start legalizing the ones in the country now, but not all at once – no broad, sweeping amnesty. It will take time, but we can integrate them into our culture with no more pain than we have our entire immigrant population, and without the economic shock of removing them all or just allowing them in and legal all at once.