LyrArc Article Gist
The Times says California has the largest part of the undocumented population in the US workng mostly in agriculture and construction, retail. Pew Research estimates 1.8 million undocumented population in the state, 800,000 in Los Angeles County alone, making up 8% of the total population. About 53% of Mexican descent and the rest from Guatemala, Salvador and Philippines.

Throughout the greater part of this century  immigrants were brought in from Mexico for agricultural work particularly in the 1930's and during World War II. Agricultural landowners needed this labor for harvests in California and other western states but agribusiness owners in Mexico favored less migration to use this labor in Mexican agriculture. This illegal migration was reversed after World War II. By 1952 there was a consensus in the country and president Eisenhower led the first mass deportation program of the US called Operation Wetback which returned 1.3 million illegal migrants back to Mexico, led by Army General Joseph Swing.