In reality, 883,706 temporary workers and their family members came to the United States in 2005, often with no intention of staying long, much less changing their citizenship. Tens of thousands of American workers likewise went abroad to work for a few years, but we don't call them emigrants or assume they are eager to surrender U.S. citizenship. Working in various countries is almost a rite of passage for managers in many multinational corporations.
As for illegal entrants, the Pew Hispanic Center figures there were about 500,000 per year from 2000 to 2005. The total number still living in the United States last year was famously (but somewhat arbitrarily) estimated at 12 million. But the same source also estimated that only 56 percent of the illegal residents were from Mexico (compared with about 30 percent from Asia), and 40 percent to 50 percent of those illegal residents arrived here legally, "mostly as tourists or business visitors."
There are now 19,173 people in federal prisons for serious immigration violations (smuggling aliens or counterfeiting credentials). There were 1.3 million apprehensions for illegal entry in 2005, and a quarter of a million people were deported. Those figures are not nearly harsh enough to please some people. They use the word "amnesty" to mean any proposal that fails to imprison or deport all the 12 million men, women and children who are thought to be living in the United States without having lined up in the proper multi-year queues (assuming queues were even available to those without relatives here).
Liberal Democrats and conservative Republicans make different excuses for leaving immigration policy just as irrational as it is -- that is, so dependent on arbitrary political preferences and long waiting lines that wholesale evasion is inevitable. Liberals and immigration lawyers won't budge an inch on leaving family unification as the ultimate criterion for legal residence, or on making permanent U.S. voters out of every temporary worker -- so they argue that we are better off with the status quo than we would be by making it any easier for any foreigners to work here without hiding in the underground economy.
A few conservatives bemoan the fact that most illegal immigrants are short of schooling, so that we are supposedly better off just keeping them illegal (though they don't put it that way) so they never qualify for Medicaid or food stamps. What both sides have in common is a pathological fear of change supported by a gaggle of misused words and a shortage of facts.