Overnight, some industries would become desperate for workers. The biggest beneficiaries would be low-skilled American workers. The big losers might surprise you.

At least 12 million illegal immigrants live in the U.S. Most pick crops, wash dishes, build houses, cut lawns and do other jobs for between $6 and $15 an hour. They make up about 5% of the total U.S. work force. But

What if we threw them all out?

Thousands of farmers and builders would go bust. Predator aircraft drones would prowl the Mexican border. And chunks of Los Angeles and Houston would look like ghost towns.
http://articles.moneycentral.msn.com/CollegeAndFamily/RaiseKids/WhatIfWeThrewOutAllTheIllegalImmigrants.aspx

so what if, What if.