This is the last of a five-part series looking at how illegal immigration affects U.S. border security, the criminal, health care and education systems, as well as the economy. Watch the series this week on FOX News Channel.
While most of the Los Angeles still sleeps at 5 a.m., "the nanny express" is already up and running.
Women from the poorest corners of the world come to work in the city as nannies and housemaids. Nannies and other laborers work hard at a wage that has many businesses openly employing illegal immigrants (search), including contractor Charlie D'Agostino.
"People aren't going to pay more for an American than a Mexican, just because they're American. I pay on ability," D'Agostino said. "All my workers get paid fair wage for their ability. I'm not going to pay $25 an hour to build a ditch. I'll get a $10 an hour guy to do that. So you pick your skilled labor and unskilled."
He added: "Other people that can better themselves by coming here and I think they deserve a chance too. We're all immigrants. Everybody is an immigrant."
According to Wall Street analysts, 8 percent of the U.S. workforce — 10 to 12 million jobs — is undocumented. And while their willingness to work cheap means lower prices on everything from produce to plumbing, some argue it displaces American workers and decreases pay across the board.
"I'm not opposed to bringing people into this country for the 'jobs no American will take,' but you have they have to prove to me that there are really those jobs that exist," said Rep. Tom Tancredo (search), R-Colo.
Unemployed Americans are numbered at 7.7 million; if illegal immigration ended tomorrow, it's questionable whether the unemployed will rush out to pick lettuce and, if they do, what the cost will be at the market.
"I just don't see that and I think using agricultural workers is a pretty good example of an industry or a whole classification of jobs that American workers aren't lining up to take," said Farrell Quinlan of the Arizona Chamber of Commerce.
But Rick Oltman of the Federal American Immigration Reform (search) says there aren't any jobs people won't work for.
Although hiring undocumented workers is illegal, the law is rarely enforced. Three out of four foreigners that enter the United States do so illegally and half are paid under the table, so they don't pay taxes.
"The bottom line is that businesses are benefiting from the cheap labor," Oltman said. "They're making extra profits and they're shifting the whole benefits package over on to the taxpayer."
Click on the video box above for a complete report by FOX News' William LaJeunesse.