Agricultural business and technology have driven the importation of foreign, that is, Mexican farm labor, for generations. This gave rise to the large undocumented population in the U.S. Here is a 70 year snaphot.
Agricultural productivity in the U.S. after World War Two has risen at a faster pace than manufacturing productivity (1.9% vs. 1.3% annually, from 1948 through 1999). Inside this productivity gain was growing use of unskilled Mexican labor.
Between 1942 and 1964, the Bracero guest worker program brought in 4.6 million farm workers. As Eduardo Porter of the New York Times observes, investment in technology generally happens when the immigrant spigot is shut, and relaxes when immigration increases. After the bracero program ended and some farm wages began to rise, machines were developed top pick tomatoes. Within a few years, by 1970, tomato harvest jobs were by by two-thirds.
But farmers still wanted more cheap hired labor. The shift from family to corporate farming after World War Two sharply increased the demand for the hired worker. In 1950, only 25% of farm labor was hired labor; by 2008, that grew to 60%. This hired labor force was filled by Mexicans.
Before the 1986, perhaps a quarter of farm workers in California were undocumented. The Act legalized over 1.1 million farm workers, known as Special Agricultural Workers. The undocumented percentage of farm workers dropped to 10%. But many of these now-legal workers moved off the farm and into better paying urban jobs. (See a 2013 analysis by Philip Martin here).
The farms were saved by a flood of new undocumented workers in 1990s. As a prior post showed, it was easy to get into the U.S. illegally. The share of California crop workers who were undocumented shot up from 10% in the late 1980s to over 50% in the late 1990s. This depressed wages. Farmers’ investments in labor-saving technology all but froze. Farmers’ capital investments fell 46.7% from their peak in 1980 through 1999.
In 2010, the average earnings of crop workers were about $9 an hour, and median weekly earnings were 60% of those of workers in comparable private-sector nonfarm jobs. The undocumented status of these workers surely accounts for much of this wage disparity. They are captive to low skilled, low paying jobs.
According to the Brookings Institute, about 60% of immigrants in farming, are “miscellaneous agricultural workers, including animal breeders,” but only 20% of native born farm workers. These workers require little more than on-the-job training, largely planting and harvesting crops, operating farm equipment, and raising animals. The higher level ”farmers and ranchers” jobs are 97% native born, only 3% foreign-born.