Salinas Valley, California. Large scale, commercial agriculture. This single California county (Monterey) shipped 20,096 carlots of lettuce in 1934, or forty-five percent of all carlot shipments in the United States. In the same year 73.8 percent of all United States carlot shipments were made from Monterey County, Imperial Valley, California (7,797 carlots) and Maricopa County, Arizona (4,697). Production of lettuce is largely in the hands of a comparatively small number of grower-shippers, many of whom operate in two or all three of these Counties. Labor is principally Mexican and Filipino in the fields, and white American in the packing sheds. Many workers follow the harvests from one valley to the other, since plantings are staggered to maintain a fairly even flow of lettuce to the Eastern markt throughout the year