Increased (but still fairly lax) border security has disrupted the lettuce industry, which depends on (nominally) illegal immigrants for labor. From As Border Tightens, Growers See Threat to ‘Winter Salad Bowl’:
At least half of the 1.8 million crop workers in the U.S. are undocumented, according to the Department of Labor. They sustain an industry valued at $30 billion annually. They also make lawbreakers out of thousands of employers who hire them to do work they say Americans are unwilling to do.All told, about 10 million illegal immigrants live in the U.S. Without them, experts say, industries like construction, lodging and agriculture would be forced to radically change how they operate — sharply boosting costs for consumers or curtailing the services they provide. An illegal work force “defines whole industries and whole sectors of the labor market,” says Doris Meissner, the immigration chief under President Clinton.