Throughout the twentieth and twenty-first centuries, farms and agricultural companies in the United States hired large numbers of Mexicans and Mexican Americans as seasonal workers. In the 1930s, the pecan industry developed a contract system whereby farms hired companies to shell the pecans, which were then sold to other businesses or consumers. The contractors who owned pecan-shelling plants found it less expensive to employ temporary laborers than to use machines to do the work. Because of high unemployment and the Great Depression, a period of especially high unemployment and low economic productivity worldwide, workers were willing to accept low wages since there were few jobs available.