Debating Illegal Labor at the New York Times

"Could Farms Survive Without Illegal Labor?"

I'm one of several debaters.  I like what Phillip Martin had to say--he's the real expert here.  Here's the intro to the broader debate:

A farmer in Maine who is raising crops sustainably told Times columnist Mark Bittman, “If the cost of food reflected the cost of production, that would change everything.” Instead, American produce is underpriced, in part because farmers and growers rely on illegal immigrant workers, who are paid little and often have poor working conditions. 

This reliance on immigrant workers has farmers lobbying against a bill that would require them to verify migrant workers' status and employ only legal workers, saying such a mandate would cripple the industry. 

If American growers are so dependent on illegal labor, would strict verification drive up prices for labor and, ultimately, produce? Are consumers too accustomed to inexpensive vegetables and fruit to accept the cost of legal labor to produce it?

I've already received email complaining about my remarks to the effect that getting rid of illegal immigrants would do little for the ranks of unemployed legals seeking work.

There is an old and largely true hypothesis in economics:  supply creates its own demand.  With regard to low-skilled immigration, one particularly compelling test of this hypothesis is an old study by David Card that examined the unemployment and wage effects of the Mariel Boatlift on the Miami labor market (PDF).  That unusual event brought about 125,000 low-skilled laborers to Miami over just a few months, about a 7% increase in the local labor market.  You might think that such an event would have caused wages to fall and unemployment to skyrocket.  But it didn't.  Neither wages nor unemployment changed.

Now, things are probably different in an environment with high unemployment.  Standard theories of recessions are the clearest exception the rule that supply creates its own demand.  But shifting supply inward--which is effectively what getting tough illegal immigrants amounts to--seems like a really bad way to deal with unemployment relative to finding a way to shift demand outward.