Immigration isn't the problem..illegal immigration is the problem. I have no problem with letting immigrants come here to do a temporary job, make some money and go home...it is when they start staying illegally and feeding at the government trough that the problems start. If they want to come here and stay..then they should be forced to jump through the immigration hoops or be sent back home.
Every job a foreigner takes lowers your neighbor's pay.
There are some jobs that Americans simply don't want to do any more...and while an immigrant temporary farm worker might add a nickel to the price of a head of lettuce, how much do you think an American who thinks he should be paid $15 an hour to pick lettuce, and get medical, dental, and FMLA benefits would add to the cost of each head? Considerably more than a nickel I would wager.
I see mexicans out in the fields in my part of the world planting and harvesting tobacco every year...if farmers had to pay Americans the wages and benefits they would expect, my bet is that the land would not even be being planted...it would probably be the site for the newest neighborhood....like we need more of those blights on the landscape..
No one wants to pick strawberries. It's hot, back-breaking work. Why should a lawyer get $300 / hour and a strawberry picker $8 / hour? It's not in the Bible. Maybe lawyers should get $100 / hour and strawberry pickers $20. Normally the market would sort out the price, but we let one segment of society pervert the market by importing cheaper humans from abroad, thereby driving down the wages of their fellow Americans. It's a sweet deal, because when their cheaper humans get sick or pop out a bambino that needs educatin' the employer can shove those costs on to taxpayers including on to those taxpayers whose wages he undercut.
I saw a study once where some economist was claiming that if all the illegals were sent home tomorrow, the price of milk would increase by two and a half times. I think I saw it in the Washington Post. If it's in the Post, you know not to trust it, so I ran the numbers. I found what jobs on dairy farms pay, for legal and illegal labor, what percentage of a dairy farms expenses go to labor, not counting the farmer and his family, how much of the wholesale price per hundredweight reflected the labor cost, mark-up in the supermarket--all that information is available-. It turned out that if all the illegals were replaced by Americans tomorrow who were paid the high salary the tough job deserves, milk would have shot up from something like 2.69 per gallon to $2.89. In other words, negligible. No one would have noticed. I used to visit economics stack exchange sometimes, and posted my findings there. All these professional economists started down voting me like crazy.